The Toylot company makes an electric train with a motor that it claims will draw an average of only 0.8 ampere (A) under a normal load. A sample of nine motors was tested, and it was found that the mean current was x= 1.22 A, with a sample standard deviation of s = 0.44 A. Do the data indicate that the Toylot claim of 0.8 A is too low? (Use a 1% level of significance.)

1. What are we testing in this problem?
a. single proportion
b. single mean

2. What is the level of significance?
3. State the null and alternate hypotheses.

4. What sampling distribution will you use? What assumptions are you making?
a. The Student's t, since we assume that x has a normal distribution with known σ
b. The standard normal, since we assume that x has a normal distribution with known σ.
c. The standard normal, since we assume that x has a normal distribution with unknown σ.
d. The Student's t, since we assume that x has a normal distribution with unknown σ.

total SA = 764 yd²

A triangular prism is 13 yards long and has a triangular face with a base of 12 yards and a height of 8 yards. The other two sides of the triangle are each 10 yards. What is the surface area of the triangular prism?

See attachment.

if length = 13 yards then total SA = 512 yd²

if length = 19 yards then total SA = 764 yd²

Answer:

D

Step-by-step explanation:

An arithmetic sequence is a series of numbers that increases or decreases by a certain quantity every step. A is not an arithmetic sequence, since it alternates between 2 and -2. B is not an arithmetic sequence, since it does not grow constantly in one direction. C is not an arithmetic sequence, but rather a geometric one. D is an arithmetic sequence, decreasing by 3 with each step. Hope this helps!

Answer:

-16x^5

Step-by-step explanation:

f(x)=x^3+10x^2-25x-250

f(x) = x^3-15x+x^2-250

f(x) = x^5-15x-250

f(x) = x^5 -x + 16

f(x) = -x^5+16

f(x) = -16x^5

// have a great day //

Answer:

Continuously

Step-by-step explanation:

Compounded continuously:

A = Pe^(rt)

A = 11,000 e^(0.0625 × 10)

A = 20,550.71

Compounded semiannually (twice per year):

A = P(1 + r)^t

A = 11,000 (1 + 0.063/2)^(2×10)

A = 11,000 (1 + 0.0315)^20

A = 20,453.96

Answer:

answer is 2/3

Step-by-step explanation:

probability it is an eclair is 1/15=3/(3+2x+6+x)= 1/(x+3)

so x+3=15 and then x = 12

so the probability it is a humbug is (2*12+6)/(3*12+9) = 30/45 = 2/3

Answer:

[tex]\dfrac{1}{12}[/tex]

Step-by-step explanation:

Probability of the captain hitting the pirate ship [tex]=\dfrac{1}{2}[/tex]

Probability of the pirate hitting the captain's ship [tex]=\dfrac{1}{6}[/tex]

If both fire cannons at the same time, the probability that both the pirate and the captain hit each other's ship

=P(Captain Hits AND Pirate Hits)

=P(Captain Hits) X P(Pirate Hits)

[tex]=\dfrac{1}{2} X \dfrac{1}{6}\\\\=\dfrac{1}{12}[/tex]

Answer:

10-19 ⇒ 4

40-49 ⇒ 3

Answer:

10-19: 4 numbers

40-49: 3 numbers

Step-by-step explanation:

10-19: 11, 13, 17, 18 (4 numbers)

40-49: 41, 44, 47 (3 numbers)

Answer:

1250

Step-by-step explanation:

5% of $5000 is 250

250X5= 1250

Answer:

0-4: Make it 2 units tall

5-9: Make it 5 units tall

10-14: Make it 1 unit tall

15-19: Make it 4 units tall

20-24: Make it 4 units tall

Step-by-step explanation:

0-4: 2, 2 (2 numbers)

5-9: 6, 7, 7, 8, 9 (5 numbers)

10-14: 14 (1 number)

15-19: 15, 16, 16, 18 (4 numbers)

20-24: 21, 23, 23, 24 (4 numbers)

Answer:

A. 90 sq. units

Step-by-step explanation:

5(18) = 90

Answer:

807,205

Step-by-step explanation:

Take the eight hundred and seven thousand and express that has 807,000. Then, add the two hundred and five at the end to get 807,205

The given statement is written in figures 807,205.

The given statement is eight hundred and seven thousand, two hundred and five in figures.

We need to write the given statement as the number.

A number is a mathematical object used to count, measure, and label. The original examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can be represented in language with number words.

Now, eight hundred and seven thousand, two hundred and five=807,205.

Therefore, the given statement is written in figures 807,205.

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Answer:

Step-by-step explanation:

Hello!

There are two values of n in the text, I'll use the one that appears in all the questions.

The variable of interest is

X: pollutants found in waterways near large cities. (ppm)

This variable has a normal distribution with parameters μ= 9ppm and σ= 1.5ppm

1) X~N(μ;σ²)

X~N(9;2.25)

2) The distribution of the sample mean is X~N(μ;σ²/n)

σ²/n= 2.25/37= 0.06

X~N(9;0.06)

3) P(X>9.6)

To calculate this probability you have to use the standard normal distribution. Using the population parameters, you can calculate the corresponding Z value:

Z= (X-μ)/σ= (9.6-9)/1.5= 0.4

P(Z>0.4)= 1-P(Z≤0.4)= 1 - 0.65542= 0.34458

The probability of selecting a city at random and finding 9.6ppm pollutants.

4) In this item, instead of calculating the probability of one value of the variable you have to calculate the probability of the sample average taking a determined value. Because of this, you have to work using the distribution of the sample mean, instead of the distribution of the variable.

P(X[bar]>9.6)

Z= (X[bar]-μ)/(σ/√n)= (9.6-9)/√0.06= 2.45

P(Z>2.45)= 1 - P(Z≤2.45)= 1 - 0.99286= 0.00714

5) The assumption of a normal distribution is not necessary for item 4. Since the sample size is large enough (greater than 30) you can apply the central limit theorem and approximate the distribution of the sample mean to normal, regarding the distribution of the original variable.

6)

In this case, you have to work starting with the standard normal distribution and then "translate" the Z values into values of the average amount of pollutants.

The first quartile divides the bottom 25% of the distribution from the top 75%, symbolically:

P(Z≤z₁)= 0.25

z₁= -0.674

z₁= (X[bar]-μ)/(σ/√n)

z₁*(√n/σ)=X[bar]-μ

X[bar]=z₁*(√n/σ)+μ

X[bar]=(-0.674)*(√37/1.5)+9= 6.27ppm

The third quartile divides the bottom 75% of the distribution from the top 25%, symbolically:

P(Z≤z₂)= 0.75

z₂= 0.674

z₂= (X[bar]-μ)/(σ/√n)

z₂*(√n/σ)=X[bar]-μ

X[bar]=z₂*(√n/σ)+μ

X[bar]=(0.674)*(√37/1.5)+9= 11.7.3ppm

IQR= Q₃-Q₁= 11.73-6.27= 5.46ppm

I hope this helps!

Answer:

   see below

Step-by-step explanation:

These are always simplified by cancelling common factors from numerator and denominator. In order to do that, you have to factor the expressions. The restrictions on x give a clue as to the factors of the denominator.

  [tex]\dfrac{x^2+5x+6}{x^2-x-6}=\dfrac{(x+3)(x+2)}{(x-3)(x+2)}=\boxed{\dfrac{x+3}{x-3}}[/tex]

The best possible statement to your question is x+3 / x-3

Answer:

The proportion of the variability seen in math achievement that can be predicted by math attitude is 0.78, the same value as the correlation coefficient.

Step-by-step explanation:

The correlation coefficient r between this two variables is found to be 0.78.

This coefficient can be calculated as:

[tex]r=\dfrac{SSY'}{SSY}[/tex]

where SSY' is the sum of the squares deviation from the mean for the predicted value and SSY is the sum of the squares deviation from the mean for the criterion variable.

Then, the value of the coefficient r is giving the proportion of the variability seen in the criterion value Y that can be explained by the predictor variable X.

Answer:

r=SSY'/SSY

Step-by-step explanation:

Answer:

(a)24

(b)8

(c)4

Step-by-step explanation:

Number of STudents in the Class = 36

Angle representing Students with Red Hair =40 degrees

Angle representing Students with Blonde Hair =240 degrees

Therefore:

(a)Number of Students with Blonde Hair

[tex]=\dfrac{240^\circ}{360^\circ} \times 36\\\\ =24$ students[/tex]

(b)Number of Students with Dark Hair

Angle representing students with dark hair = 360-(240+40)=80 degrees

Therefore:

Number of Students with Dark Hair

[tex]=\dfrac{80^\circ}{360^\circ} \times 36\\\\ =8$ students[/tex]

(c)Number of Students with Blonde Hair

[tex]=\dfrac{40^\circ}{360^\circ} \times 36\\\\ =4$ students[/tex]

There are 8 students that have blond hair

There are 24 students that have dark hair

There are 4 students that have red hair

Please find attached the pie chart used in answering this question

A pie chart is a graph that displays information in a circle. The circle is divided into slices which represent a numerical proportion. The sum of angles in a pie chart is 360 degrees

To determine the number of students with a type of hair, use this formula :

(degree of the slice that represents the hair type / 360) x total number of students in the class

Degree of the slice that represents blond hair = 360 - (240 + 40) = 80

Students that have blonde hair = [tex]\frac{80}{360}[/tex]  x 36 = 8

Students that have dark hair = [tex]\frac{240}{360}[/tex] x 36 = 24

Students that have red hair = [tex]\frac{40}{360}[/tex] x 36 = 4

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Answer:

x = 12

Step-by-step explanation:

g(x)= 2x-4

g(x)= 20

Therefore,

2x-4 = 20

Bringing -4 to the other side it becomes positive,so..

2x= 20+4

= 24

x =24/2

= 12

Answer:

B:

Step-by-step explanation:

According to theorem, "the angle in a semi-circle is a right angle" So,

<O = 90°

<M = 54

<K = 180-90-54

<OKM = 36°

Answer:

88/57

Step-by-step explanation:

Answer: 88:57

Step-by-step explanation:

Length is 88 and width is 57

So the ratio is 88:57

Answer:

Step-by-step explanation:

Solve for y to put the equation in slope-intercept form.

  3x = 4y -4 . . . . . eliminate parentheses, collect terms

  3x +4 = 4y . . . . . add 4

  y = 3/4x +1 . . . . . divide by 4

The slope is the x-coefficient: 3/4.

The y-intercept is the constant: 1.

Answer:

  C.  y ≤ 1

Step-by-step explanation:

The maximum value of the function is 1. So, the range is all values of y less than or equal to that.

  y ≤ 1

Answer:

I think the complete question should be:

A researcher has developed a new drug designed to reduce blood pressure. In an experiment, 21 subjects were assigned randomly to the treatment group and received the new experimental drug. The other 23 subjects were assigned to the control group and received a standard well known treatment. After a suitable period of time, the reduction in blood pressure for each subject was recorded.

Treatment group n = 21, x1 mean = 23.48, sd = 8.01

Control group n = 23, x2 = 18.52, sd = 7.15

Based on these data, the computed two-sample t statistic is:

Step-by-step explanation:

Since the variances to be calculated from the sd are unequal we use this formula:

t statistics = (x1 - x2) / [(sd1²/n1) + (sd2²/n2) where n1 = 21, x1 mean = 23.48, sd1 = 8.01, n2 = 23, x2 = 18.52, sd2 = 7.15

Thus, we have

test statistic= (23.48-18.52) / [(8.01²/21) + (7.15²/23)]

Test statistics = 4.96 / (324.36/21)+(51.12/23)]

Test statistics = 4.96/ (15.45+2.43)

t statistic = 4.96 / 17.88

t statistics = 0.2774

I hope that helps, you can use this to solve for tours if the values are not the same

Answer:

A.

Step-by-step explanation:

So first you need to find the slope:

[tex]\frac{-2-6}{3+2} =-\frac{8}{5}[/tex]

Since it's point slope, you have to use a point:

It's either:

[tex](y - 6)=-\frac{8}{5}(x+2)[/tex]

or

[tex](y+2)=-\frac{8}{5}(x-3)[/tex]

Check which answer has those:

A.

The solution is Option A.

The equation of line is y - 6 = ( -8/5 ) ( x + 2 ) where the slope is -8/5

The equation of a line is expressed as y = mx + b where m is the slope and b is the y-intercept

And y - y₁ = m ( x - x₁ )

y = y-coordinate of second point

y₁ = y-coordinate of point one

m = slope

x = x-coordinate of second point

x₁ = x-coordinate of point one

The slope m = ( y₂ - y₁ ) / ( x₂ - x₁ )

Given data ,

Let the equation of line be represented as A

Now , the value of A is

Let the first point be P ( -2 , 6 )

Let the second point be Q ( 3 , -2 )

The slope of the line between the point is given by m = ( y₂ - y₁ ) / ( x₂ - x₁ )

Substituting the values in the equation , we get

Slope m = ( 6 - ( - 2 ) ) / ( -2 - 3 )

On simplifying the equation , we get

Slope m = ( 8 / -5 ) = -8/5

Now , the equation of line is y - y₁ = m ( x - x₁ )

Substituting the values in the equation , we get

y - 6 = ( -8/5 ) ( x - ( -2 ) )

On simplifying the equation , we get

y - 6 = ( -8/5 ) ( x + 2 )

Hence , the equation of line is y - 6 = ( -8/5 ) ( x + 2 )

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Answer:

26.68% probability that exactly three will end up being replaced under warranty

Step-by-step explanation:

For each telephone under warranty, there are only two possible outcomes. Either they need to be replaced, or they do not need to be replaced. Each telephone is independent of other telephones. So we use the binomial probability distribution to solve this question.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]

In which [tex]C_{n,x}[/tex] is the number of different combinations of x objects from a set of n elements, given by the following formula.

[tex]C_{n,x} = \frac{n!}{x!(n-x)!}[/tex]

And p is the probability of X happening.

30% must be replaced with new units

This means that [tex]p = 0.3[/tex]

If a company purchases ten of these telephones, what is the probability that exactly three will end up being replaced under warranty

This is [tex]P(X = 3)[/tex] when [tex]n = 10[/tex]. So

[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]

[tex]P(X = 3) = C_{10,3}.(0.3)^{3}.(0.7)^{7} = 0.2668[/tex]

26.68% probability that exactly three will end up being replaced under warranty

Answer:

Step-by-step explanation:

a) The number of students sampled in both populations are large. We can assume that the populations are normally distributed. The populations are also independent.

b) This is a test of 2 independent groups. Let μ1 be the mean responses of students buying lecture notes and μ2 be the mean responses of students not buying lecture notes.

The random variable is μ1 - μ2 = difference in the mean responses of students buying lecture notes and the mean responses of students not buying lecture notes.

We would set up the hypothesis.

The null hypothesis is

H0 : μ1 = μ2 H0 : μ1 - μ2 = 0

The alternative hypothesis is

H1 : μ1 ≠ μ2 H1 : μ1 - μ2 ≠ 0

This is a two tailed test.

Since sample standard deviation is known, we would determine the test statistic by using the t test. The formula is

(x1 - x2)/√(s1²/n1 + s2²/n2)

From the information given,

x1 = 8.48

x2 = 7.8

s1 = 0.94

s2 = 2.99

n1 = 86

n2 = 35

t = (8.48 - 7.8)/√(0.94²/86 + 2.99²/35)

t = 1.32

The formula for determining the degree of freedom is

df = [s1²/n1 + s2²/n2]²/(1/n1 - 1)(s1²/n1)² + (1/n2 - 1)(s2²/n2)²

df = [0.94²/86 + 2.99²/35]²/[(1/86 - 1)(0.94²/86)² + (1/35 - 1)(2.99²/35)²] = 0.0706/0.00192021883

df = 37

We would determine the probability value from the t test calculator. It becomes

p value = 0.195

c) Since alpha, 0.01 < than the p value, 0.195, then we would fail to reject the null hypothesis. Therefore, at 5% significance level, the samples do not provide sufficient evidence to conclude that there is a difference in the mean responses of the two groups of the students.

d) The formula for determining the confidence interval for the difference of two population means is expressed as

Confidence interval = (x1 - x2) ± z√(s²/n1 + s2²/n2)

For a 99% confidence interval, the z score is 1.2.58. This is determined from the normal distribution table.

x1 - x2 = 8.48 - 7.8 = 0.68

z√(s1²/n1 + s2²/n2) = 2.58√(0.94²/86 + 2.99²/35) = 1.33

The confidence interval is

0.68 ± 1.33

The upper boundary for the confidence interval is

0.68 + 1.01 = 2.01

The lower boundary for the confidence interval is

0.68 - 1.33 = - 0.65

We are confident that the difference in population means responses between the students buying lecture notes and the students not buying lecture notes is between - 0.65 and 2.01

d) For a 95% confidence interval, the z score is 1.96.

z√(s1²/n1 + s2²/n2) = 1.96√(0.94²/86 + 2.99²/35) = 1.01

The confidence interval is

0.68 ± 1.01

The upper boundary for the confidence interval is

0.68 + 1.01 = 1.69

The lower boundary for the confidence interval is

0.68 - 1.01 = - 0.33

Therefore, a 95% confidence interval for (μ1-μ2) would be narrower. This is seen in the values in both scenarios.

Answer:

cos =1/ sec

=8/17

tan =1/cot

= -15/8

sin = 15/17 or -15/17

cosec = 1/ sin

= 17/15 or -17/15

Answer:

Did the same assignment. lol can see how that went but here's the answers. hope it helps.

Answer:

The last option is the correct choice 33.5

Step-by-step explanation:

[tex]V=\pi r^2\frac{h}{3} \\=\pi 2^2\frac{8}{3} \\=33.51\\=33.5[/tex]

Answer:

D

Step-by-step explanation:

In the attached file

Answer:

A) The probability that a randomly selected medical student who took the test had a total score that was less than 484 = 0.06178

B) The probability that a randomly selected study participant's response was between 504 and 516 = 0.29019

C) The probability that a randomly selected study participant's response was more than 528 = 0.00357

D) Option D is correct.

Only the event in (c) is unusual as its probability is less than 0.05.

Step-by-step explanation:

The b and c parts of the question are not complete.

B) Find the probability that a randomly selected study participant's response was between 504 and 516

C) Find the probability that a randomly selected study participant's response was more than 528.

D) Identify any unusual event amongst the three events in A, B and C. Explain the reasoning.

a) None.

b) Events A and B.

C) Event A

D) Event C

Solution

This is a normal distribution problem with

Mean = μ = 500

Standard deviation = σ = 10.4

A) Probability that a randomly selected medical student who took the test had a total score that was less than 484 = P(x < 484)

We first normalize or standardize 484

The standardized score for any value is the value minus the mean then divided by the standard deviation.

z = (x - μ)/σ = (484 - 500)/10.4 = - 1.54

To determine the required probability

P(x < 484) = P(z < -1.54)

We'll use data from the normal distribution table for these probabilities

P(x < 484) = P(z < -1.54) = 0.06178

B) Probability that a randomly selected study participant's response was between 504 and 516 = P(504 ≤ x ≤ 516)

We normalize or standardize 504 and 516

For 504

z = (x - μ)/σ = (504 - 500)/10.4 = 0.38

For 516

z = (x - μ)/σ = (516 - 500)/10.4 = 1.54

To determine the required probability

P(504 ≤ x ≤ 516) = P(0.38 ≤ z ≤ 1.54)

We'll use data from the normal distribution table for these probabilities

P(504 ≤ x ≤ 516) = P(0.38 ≤ z ≤ 1.54)

= P(z ≤ 1.54) - P(z ≤ 0.38)

= 0.93822 - 0.64803

= 0.29019

C) Probability that a randomly selected study participant's response was more than 528 = P(x > 528)

We first normalize or standardize 528

z = (x - μ)/σ = (528 - 500)/10.4 = 2.69

To determine the required probability

P(x > 528) = P(z > 2.69)

We'll use data from the normal distribution table for these probabilities

PP(x > 528) = P(z > 2.69) = 1 - P(z ≤ 2.69)

= 1 - 0.99643

= 0.00357

D) Only the event in (c) is unusual as its probability is less than 0.05.

Hope this Helps!!!

Answer:

D: 15 and 2

Step-by-step explanation:

Mean

To find the mean, or average, add up all the values in the data set,then divide by the number of values in the data set.

1. Add up all the values

Values: 14, 14, 15, 15, 16, 15, 15, 16

Add them :14+14+15+ 15+16+15+15+16=120

120

2. Divide by the number of values

Count how many numbers are in the data set. In this case there are 8. Divide 120 by 8.

120/8=15

The mean is 15

Range

To find the range, subtract the smallest number in the set from the biggest number in the set.

14, 14, 15, 15, 16, 15, 15, 16

Biggest number: 16

Smallest number: 14

biggest-smallest

16-14=2

The range is 2

Therefore, the answer is D: 15 and 2

observation means number.

mean= sum of all observation ÷ number of observation

= 14+ 14+ 15+ 15+ 16+ 15+ 16

7

= 105

7

= 15

range= the highest observation - lowest observation

= highest number- 16

lowest number- 14

= 16-14

= 2

therefore the answer is

OPTION- D 15;2

Answer:

a) The probability mass function of K = [tex]P(K=k) = \binom{k-1}{4}0.1^{4}*0.9^{k-5} ; k =5,6,...[/tex]

b)

c)

Step-by-step explanation:

a) Let p be  the probability of winning each ticket be = 0.1

Then q which is the probability of failing each ticket  = 1 - p = 1  - 0.1 = 0.9

Assume X represents the  number of failure preceding the 5th success in x + 5 trials.

The last trial must be success whose probability is p = 0.1 and in the remaining (x + r- 1) ( x+ 4 ) trials we must have have (4) successes whose probability is given by:

[tex]\binom{x+r-1}{r-1}*p^{r-1}*q^{x} = \binom{x+4}{4}0.1^{4}*0.9^{x} ; x =0, 1, .........[/tex]

Then, the probability distribution of random variable X is

[tex]P(X=x) = \binom{x+4}{4}0.1^{4}*0.9^{x} ; x =0, 1, .........[/tex]

where;

X represents the  negative binomial random variable.

K= X + 5 = number of ticket buy up to and including fifth winning ticket.

Since K =X+5 this signifies that  X = K-5

as X takes value 0, 1 ,2,...

K takes value 5, 6 ,...

Therefore:

The probability mass function of K = [tex]P(K=k) = \binom{k-1}{4}0.1^{4}*0.9^{k-5} ; k =5,6,...[/tex]

b)

Let p represent the probability of getting a tail on a flip of the coin

Thus p = 0.5 since it is a fair coin

where L = number of flips of the coin including 33rd occurrence of  tails

Thus; the negative binomial distribution of L can be illustrated as:

[tex]P(X=x) = \binom{x-1}{r-1}(1-p)^{x-r}p^r[/tex]

where

X= L

r = 33  &

p = 0.5

Since we are looking at the 33rd success; L is likely to be : L = 33,34,35...

Thus; the PMF of L = [tex]P(L=l) = \binom{l-1}{33-1}(1-0.5)^{l}(0.5)^{33} \\ \\ \\ \mathbf{P(L=l) = \binom{l-1}{33-1}(0.5)^{l} }[/tex]

c)  

Given that:

Let  M be the random variable which represents  the number of tickets need to be bought to get the first success,

also success probability is 0.01.

Therefore, M ~ Geo(0.01).

Thus, the PMF of M is given by:

[tex]P(M = m) = (1-0.01)^{m-1} * 0.01 , \ \ \ since \ \ \ (m = 1,2,3,4,....)[/tex]

[tex]P(M=m) = (0.99)^{m-1} * 0.01 , m = 1,2,3,4,....[/tex]

Answer:

The  90% confidence interval for the difference between proportions is (0.115, 0.228).

As the value 0 is not included in the interval, we can conclude that there is significant difference in the proportion of youger adults that use the horn and older adults that use the horn.

Step-by-step explanation:

We want to calculate the bounds of a 90% confidence interval.

For a 90% CI, the critical value for z is z=1.645.

The sample 1 (younger adults) , of size n1=501 has a proportion of p1=0.521.

[tex]p_1=X_1/n_1=261/501=0.5210[/tex]

The sample 2 (older  adults), of size n2=352 has a proportion of p2=0.3494.

[tex]p_2=X_2/n_2=123/352=0.3494[/tex]

The difference between proportions is (p1-p2)=0.1715.

[tex]p_d=p_1-p_2=0.5210-0.3494=0.1715[/tex]

The pooled proportion, needed to calculate the standard error, is:

[tex]p=\dfrac{X_1+X_2}{n_1+n_2}=\dfrac{261+123}{501+352}=\dfrac{384}{853}=0.4502[/tex]

The estimated standard error of the difference between means is computed using the formula:

[tex]s_{p1-p2}=\sqrt{\dfrac{p(1-p)}{n_1}+\dfrac{p(1-p)}{n_2}}=\sqrt{\dfrac{0.4502*0.5498}{501}+\dfrac{0.4502*0.5498}{352}}\\\\\\s_{p1-p2}=\sqrt{0.0005+0.0007}=\sqrt{0.0012}=0.0346[/tex]

Then, the margin of error is:

[tex]MOE=z \cdot s_{p1-p2}=1.645\cdot 0.0346=0.0569[/tex]

Then, the lower and upper bounds of the confidence interval are:

[tex]LL=(p_1-p_2)-z\cdot s_{p1-p2} = 0.1715-0.0569=0.115\\\\UL=(p_1-p_2)+z\cdot s_{p1-p2}= 0.1715+0.0569=0.228[/tex]

The  90% confidence interval for the difference between proportions is (0.115, 0.228).