A sample proportion is calculated from a sample size of 391. How large of a sample would we need in order to decrease the standard error by a factor

A sample proportion is calculated from a sample size of 391. How large of a sample would we need in order to decrease the standard error by a factor of 8?

Question 1 options:

1) 3,128

2) 782

3) 1,106

4) 25,024

5) 3,910

Question 2

To design a new advertising campaign, Ford Motor Company would like to estimate the proportion of drivers of the new Ford Fusion that are women. In a random sample of 81 Fusion owners, 36 of them were women. What is the 99% confidence interval estimating the proportion of all drivers who are women?

Question 2 options:

1) ( 0.41334 , 0.69777 )

2) ( 0.30223 , 0.58666 )

3) ( 0.38923 , 0.49966 )

4) ( 0.316 , 0.57289 )

5) ( -0.30223 , 0.58666 )

Question 3

The Student Recreation Center wanted to determine what sort of physical activity was preferred by students. In a survey of 78 students, 61 indicated that they preferred outdoor exercise over exercising in a gym. The 99% confidence interval estimating the proportion of all students at the university who prefer outdoor exercise is given by which of the following?

Question 3 options:

1) ( 0.6733 , 0.8908 )

2) ( 0.09754 , 0.33836 )

3) ( 0.66164 , 0.90246 )

4) ( 0.7353 , 0.8288 )

5) ( -0.66164 , 0.90246 )

Question 4

You are watching a nightly news broadcast on CNN and the reporter says that a 95% confidence interval for the proportion of Americans who supported going to war in Iraq was ( 0.3099 , 0.3701 ). You also note that the footnote says this is based on a random sample performed by Gallup with 950 respondents. What is the correct interpretation of this confidence interval?

Question 4 options:

1) We are 95% confident that the proportion of all Americans who supported going to war in Iraq is between 0.3099 and 0.3701.

2) We are certain that 95% of Americans will be between 0.3099 and 0.3701.

3) We are 95% confident that the proportion of all Americans surveyed who supported going to war in Iraq is between 0.3099 and 0.3701.

4) We are 95% condfident that of the 950 repspondents, between 0.3099 and 0.3701 of them supported the decision to go to war.

5) We cannot determine the proper interpretation of this interval.

Question 5

The Student Recreation Center wanted to determine what sort of physical activity was preferred by students. In a survey of 68 students, 47 indicated that they preferred outdoor exercise over exercising in a gym. They estimated the proportion of students at the university who prefer outdoor exercise as ( 0.5466 , 0.8357 ), with 99% confidence. Which of the following is an appropriate interpretation of this confidence interval?

Question 5 options:

1) We are 99% confident that the proportion of exercise time which the average student spends outdoors is between 0.5466 and 0.8357.

2) We are 99% confident that the proportion of all students at the university who prefer outdoor exercise is between 0.5466 and 0.8357.

3) We are 99% confident that the proportion of students surveyed who prefer outdoor exercise is between 0.5466 and 0.8357.

4) We cannot determine the proper interpretation of this interval.

5) We are certain that 99% of students will be between 0.5466 and 0.8357.

Question 6

The Student Recreation Center wanted to determine what sort of physical activity was preferred by students. In a survey of 81 students, 52 indicated that they preferred outdoor exercise over exercising in a gym. When estimating the proportion of all students at the university who prefer outdoor exercise with 99% confidence, what is the margin of error?

Question 6 options:

1) 0.0073

2) 0.0533

3) 0.1241

4) 0.0153

5) 0.1374

Question 7

The Department of Transportion (DOT) is attempting to determine the proportion of drivers who require all passengers in the car to wear their seatbelt before putting the vehicle in drive. A survey of 74 drivers is performed and 29 people say they will not drive until all passengers in the vehicle are buckled up. To report their finding they want to do 90% confidence interval. What would be the margin error for this confidence interval?

Question 7 options:

1) 0.0726

2) 0.0108

3) 0.0053

4) 0.0931

5) 0.0567

Question 8

Based on past data, the proportion of Major League Baseball (MLB) players who bat left handed was 0.473. You are interested to see if this is still the case. Zack conduct a sample of 48 players and find that 17 are left handed hitters. The 90% confidence interval is ( 0.2406 , 0.4677 ). What is the best conclusion of those listed below?

Question 8 options:

1) The confidence interval does not provide enough information to form a conclusion.

2) The proportion of MLB players who used to be left handed from 0.473 is 90%.

3) We can not claim that the proportion of MLB players who are left handed hitters differs from 0.473.

4) We can conclude that the proportion of MLB players who are left handed hitters is smaller than 0.473.

5) We can claim that the proportion of MLB players who are left handed hitters is larger than 0.473.

Question 9

Based on past data, the proportion of Major League Baseball (MLB) players who bat left handed was 0.678. You are interested to see if this is still the case. Jack conduct a sample of 32 players and find that 11 are left handed hitters. The 90% confidence interval is ( 0.2056 , 0.4819 ). What is the best conclusion of those listed below?

Question 9 options:

1) We can conclude that the proportion of MLB players who are left handed hitters is larger than 0.678.

2) The proportion of MLB players who used to be left handed from 0.678 is 90%.

3) We can not claim that the proportion of MLB players who are left handed hitters differs from 0.678.

4) We can conclude that the proportion of MLB players who are left handed hitters is smaller than 0.678.

5) The confidence interval does not provide enough information to form a conclusion.

Question 10

Jack owns a small storefront retail business and are interested in determining the average amount of money a typical customer spends per visit to your store. Jack take a random sample over the course of a month for 12 customers and find that the average dollar amount spent per transaction per customer is $114.892 with a standard deviation of $17.6129. Jack must make 95% confidence interval for the true average spent for all customers per transaction.

Question 10 options:

1) (-103.7012, 126.0828)

2) (103.8130924, 125.9709076)

3) (109.8076, 119.9764)

4) (103.7012, 126.0828)

5) (112.691, 117.093)

Question 11

Suppose that Sami want to determine the average height of college basketball players in NCAA Division I. In a random sample of 11 players, the sample average is 73.21 inches with a standard deviation of 5.136 inches. What is the 99% confidence interval for the average height of all NCAA D-I players?

Question 11 options:

1) (-68.3008, 78.1192)

2) (71.661, 74.759)

3) (70.0407, 76.3793)

4) (68.3008, 78.1192)

5) (68.39261, 78.02739)

Question 12

Suppose you work for Fender Guitar company and you are responsible for testing the integrity of a new formulation of guitar strings. To perform your analysis, you randomly select 55 'high E' strings and put them into a machine that simulates string plucking thousands of times per minute. Zack record the number of plucks each string takes before failure and compile a dataset. Zack find that the average number of plucks is 5,658.4 with a standard deviation of 237.44. A 90% confidence interval for the average number of plucks to failure is (5,604.82, 5,711.98). From the option listed below, what is the appropriate interpretation of this interval?

Question 12 options:

1) We are certain that 90% of the average number of plucks to failure for all 'high E' strings will be between 5,604.82 and 5,711.98.

2) We are 90% confident that the proportion of all 'high E' guitar strings fail with a rate between 5,604.82 and 5,711.98.

3) We are 90% confident that the average number of plucks to failure for all 'high E' strings tested is between 5,604.82 and 5,711.98.

4) We cannot determine the proper interpretation of this interval.

5) We are 90% confident that the average number of plucks to failure for all 'high E' strings is between 5,604.82 and 5,711.98.

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