BAN 280 Final Exam

A company wishes to research consumer reaction to a new bottle design for a popular soft drink. A sample of 25 consumers are asked to rate the new bottle design. The mean and the standard deviation of the 25 ratings are 30.35 and 3.11 respectively. What is the 95% confidence interval for the population mean? a) (27.24, 33.46) b) (29.13, 31.47) c) (29.07, 31.63) d) (28.39, 32.31)

(29.07, 31.63)

Researchers are concerned about the impact of students working while they are enrolled in classes, and they'd like to know if students work too much and therefore are spending less time on their classes than they should be. First, the researchers need to find out how many hours a week students are working on average. A survey of 200 students showed that they worked an average of 7.10 hours per week. The population standard deviation of this variable is about 5 hours. What is the 95% confidence interval for the population mean? a) (6.10,8.10) b) (6.41,7.79) c) (6.57,7.63) d) (7.10,8.48)

(6.41,7.79)

A company is interested in estimating the mean number of days of sick leave taken by its employees. They randomly select 16 personnel files and notes the number of sick days taken by each employee. The mean days of sick leave for these 16 people was 12.2 days, with a standard deviation of 10 days. The 90% confidence interval (rounded to two decimals) is a) (8.09,19.21) b) (7.3,17.1) c) (7.82,16.58) d) (5.76,18.64)

(7.82,16.58)

Which of the following is a valid value for a p-value? a) 1.645 b) -0.05 c) 0.001 d) 1.96

0.001

MNM Corporation gives each of its employees an aptitude test. The scores on the test are normally distributed with a mean of 75 and a standard deviation of 15. A simple random sample of size 25 is taken from a population of 500. What is the probability that the average aptitude test score in the sample will be equal to or greater than 82? a) 0.1808 b) 0.3192 c) 0.4901 d) 0.0099

0.0099

What is the probability that the standard normal random variable Z will be less than -1.35 (negative 1.35) a) 0.4115 b) -0.4115 c) 0.0885 d) 0.4032

0.0885

Time spent by office workers using email per session is normally distributed with a mean, mu, of 8 minutes and a standard deviation, sigma, of 2 minutes. A random sample of 25 workers was selected. What is the standard error of the mean? a) 0.4 b) 0.08 c) 1.6 d) 0.32

0.4

Researchers are concerned about the impact of students working while they are enrolled in classes, and they'd like to know if students work too much and therefore are spending less time on their classes than they should be. First, the researchers need to find out how many hours a week students are working on average. A survey of 200 students showed that they worked an average of 7.10 hours per week. The population standard deviation of this variable is about 5 hours. What is the margin of error for a 95% confidence interval? a) 0.35 b) 0.69 c) 1.96 d) 1.645

0.69

Time spent by office workers using email per session is normally distributed with a mean, mu, of 8 minutes and a standard deviation, sigma, of 2 minutes. A random sample of 25 workers was selected. What is the probability that the average time spent reading email for this sample is more than 7.5 minutes? a) 0.3944 b) 0.0987 c) 0.8944 d) 0.50987

0.8944

The power level in a hypothesis test is indicated by the symbol a) beta b) 1 - sigma c) 1 - beta d) sigma

1 - beta

What is the interquartile range for the following data? 6 22 13 2 18 28 26 9 18 28 a) 17 b) 9 c) 11 d) 22

17

A company wishes to research consumer reaction to a new bottle design for a popular soft drink. A sample of 25 consumers are asked to rate the new bottle design. The mean and the standard deviation of the 25 ratings are 30.35 and 3.11 respectively. What is the critical value for a 95% confidence interval? a) 1.711 b) 1.96 c) 1.645 d) 2.064

2.064

You are the manager of a fast-food restaurant. Lately, customers have been complaining that the waiting time to place an order at your restaurant is too long. You know that in the past the mean time to place an order has been 4.5 minutes, and you wish to see if this has increased recently. You select a sample of 25 orders during a one-hour period. The mean time to place an order for these 25 orders was 5.1 minutes with a standard deviation of 1.2 minutes. Using a significance level of 0.05, test whether the mean time to place an order has increased. The Test Statistic for this test is: a) -0.5 b) 2.5 c) 0.5 d) -2.5

2.5

You are given that a 99% confidence interval for a population mean is (12,28). The sample mean used to construct this confidence interval was a) 15 b) 20 c) cannot say without the margin of error d) cannot say without the sample size

20

MNM Corporation gives each of its employees an aptitude test. The scores on the test are normally distributed with a mean of 75 and a standard deviation of 15. A simple random sample of size 25 is taken from a population of 500. What is the standard error of the mean? a) 3 b) 5 c) 15 d) 0.67

3

MNM Corporation gives each of its employees an aptitude test. The scores on the test are normally distributed with a mean of 75 and a standard deviation of 15. A simple random sample of size 25 is taken from a population of 500. What is the standard error of the sampling distribution of the sample mean? a) 3 b) 5 c) 15 d) 0.67

3

The critical value to construct a 99% confidence interval with sigma unknown for a sample size of 10 is a) 2.576 b) 1.833 c) 1.96 d) 3.250

3.250

A company is interested in estimating the mean number of days of sick leave taken by its employees. They randomly select 16 personnel files and notes the number of sick days taken by each employee. The mean days of sick leave for these 16 people was 12.2 days, with a standard deviation of 10 days. For a 90% confidence interval, the margin of error is a) 4.38 b) 4.11 c) 7.38 d) 2.5

4.38

The variance of sample of 100 observations equals 1600. The standard deviation for this sample is: a) 16 b) 40 c) 10 d) 160

40

MNM Corporation gives each of its employees an aptitude test. The scores on the test are normally distributed with a mean of 75 and a standard deviation of 15. A simple random sample of size 25 is taken from a population of 500. What is the mean of the sampling distribution of the sample mean? a) 15 b) 75 c) 3 d) 5

75

Customer waiting times at a bank have a normal distribution with mean of 6 minutes and standard deviation of 1.5 minutes. Use the Empirical Rule to estimate the percentage of customers who had to wait 3 minutes or longer. a) 95% b) 47.5% c) 97.5% d) 13.5%

97.5%

Toby's Trucking Company determined that the distance traveled per truck per year is normally distributed with a mean of 500,000 miles and a standard deviation of 10,000 miles. What percent of their trucks travel more than 25,000 miles per year? a) 49.38% b) 0.62% c) 99.38% d) 6.2%

99.38%

Based on the p-value, what is our decision and conclusion for this test? a) Do not Reject Ho. There is insufficient evidence to show that the mean time to place an order has increased b) Reject Ho. There is insufficient evidence to show that the mean time to place an order has increased c) Do not reject Ho. There is sufficient evidence to show that the mean time to place an order has increased d) Reject Ho. There is sufficient evidence to show that the mean time to place an order has increased

Reject Ho. There is sufficient evidence to show that the mean time to place an order has increased

Researchers are concerned about the impact of students working while they are enrolled in classes, and they'd like to know if students work too much and therefore are spending less time on their classes than they should be. First, the researchers need to find out how many hours a week students are working on average. A survey of 200 students showed that they worked an average of 7.10 hours per week. The population standard deviation of this variable is about 5 hours. All else remaining the same, if the confidence level were decreased to 90%, what happens to the width of the confidence interval? a) stays the same b) becomes wider c) becomes narrower d) becomes zero

becomes narrower

A company wishes to research consumer reaction to a new bottle design for a popular soft drink. A sample of 25 consumers are asked to rate the new bottle design. The mean and the standard deviation of the 25 ratings are 30.35 and 3.11 respectively. All else remaining the same, if the confidence level were increased to 99%, what happens to the standard error of the mean? a) stays the same b) becomes wider c) becomes narrower d) becomes zero

becomes wider

You are the manager of a fast-food restaurant. Lately, customers have been complaining that the waiting time to place an order at your restaurant is too long. You know that in the past the mean time to place an order has been 4.5 minutes, and you wish to see if this has increased recently. You select a sample of 25 orders during a one-hour period. The mean time to place an order for these 25 orders was 5.1 minutes with a standard deviation of 1.2 minutes. Using a significance level of 0.05, test whether the mean time to place an order has increased. The p-value for this test is: a) Between 0.01 and 0.025 b) < 0.005 c) between 0.005 and 0.01 d) none of the above

between 0.005 and 0.01

When data is collected from all members of a population, the data is called a) sample data b) time-series data c) census data d) cross-sectional data

census data

A building inspector wishes to test if a building is safe or not. His null and alternative in words are: Ho: building is not safe vs Ha: building is safe. What is the Type I error? a) concluding that the building is not safe when it is really safe b) concluding that the building is safe when it is really not safe c) concluding that the building is either safe or unsafe d) there really should be no error if he is a good building inspector

concluding that the building is safe when it is really not safe

As the sample size increases, the standard error of the mean a) also increases b) decreases c) stays the same d) depends on the confidence level

decreases

The null hypothesis usually represents: a) the ideas that the researcher/decision maker would like to prove b) very negative ideas c) the perceptions of the sample population d) existing beliefs about the population

existing beliefs about the population

In a sample, when the data are positively (right) skewed, the mean is usually a) greater than the median b) less than the median c) equal to the median d) positive

greater than the median

A company wishes to research consumer reaction to a new bottle design for a popular soft drink. A sample of 25 consumers are asked to rate the new bottle design. The mean and the standard deviation of the 25 ratings are 30.35 and 3.11 respectively. The researchers then felt that the 95% confidence interval was too wide. However, they wished to retain the same confidence level. How can they make the interval more precise (narrow)? a) decrease the sample mean b) decrease sample size c) increase sample size d) decrease the critical value

increase sample size

Researchers are concerned about the impact of students working while they are enrolled in classes, and they'd like to know if students work too much and therefore are spending less time on their classes than they should be. First, the researchers need to find out how many hours a week students are working on average. A survey of 200 students showed that they worked an average of 7.10 hours per week. The population standard deviation of this variable is about 5 hours. The researchers felt that the 95% confidence interval was too wide. However, they wished to retain the same confidence level. How can they make the interval more precise (narrow)? a) decrease the sample mean b) increase sample size c) decrease sample size d) decrease the population mean

increase sample size

If the population has a normal distribution, the sampling distribution of the sample mean a) is normal for samples of size thirty or greater b) is normal for any sample size c) has a uniform distribution d) does not exist

is normal for any sample size

If the sample size is double, what happens to the standard error of the mean? a) it goes up b) it stays the same c) it goes down d) it depends on the X variable

it goes down

If the sample size is doubled, what happens to the standard error of the mean? a) it goes up b) it stays the same c) it goes down d) it depends on the X variable

it goes down

In confidence intervals, a change in sample size (while keeping other values constant) results in a change in the a) sample mean b) population mean c) confidence level d) margin of error

margin of error

The statistic x bar is the point estimator of a) mu b) sigma c) beta d) alpha

mu

If we have a normal population, and we draw all samples of size 5 from this population, what shape will the sampling distribution of sample means be according to the Central Limit Theorem? a) skewed b) cannot say c) normal d) t-distribution

normal

The p-value of a hypothesis test is 0.02. What are your decisions at the 0.01 and the 0.05 levels of significance? a) Reject Ho at both levels of significance b) Do not reject Ho at both levels of significance c) Reject Ho at the 0.01 level but do not reject Ho at the 0.05 level d) Reject Ho at the 0.05 level but do not reject Ho at the 0.01 level

reject Ho at the 0.05 level but do not reject Ho at the 0.01 level

The standard deviation of the sampling distribution is called the a) sampling error b) margin of error c) standard error d) sample standard deviation

standard error

In hypothesis testing, what do we initially assume? a) that the alternative hypothesis is true b) that the null hypothesis is true c) that neither hypothesis is true d) that both hypotheses are true

that the null hypothesis is true

Which of the following is a continuous variable? a) whether a person is a male or female b) the distances between cities in miles c) the daily number lobsters sold at a restuarant d) number of planes at an airport

the distances between cities in miles

All else remaining the same, if the sample mean were 15 instead of 12.2, which of the following would change? a) standard error of the mean b) margin of error c) the lower upper bounds of the interval d) nothing would change

the lower upper bounds of the interval

In hypothesis testing, the significance level is the same as a) the probability of making a Type I error b) the probability of making a Type II error c) the confidence level d the power of the test

the probability of making of Type I error

From the following, identify the continuous variable a) your letter grade for BAN 280 b) the weights of football players on a team c) the number of heads that come up when a coin is tossed ten times d) the makes of cars in a parking lot

the weights of football players on a team

If we reject the null hypothesis when the null is actually false, we are committing a a) Type I error b) Type II error c) Type III error d) we are not committing an error

we are not committing any error

All else remaining the same, if you decide to increase the confidence level to 95%, the confidence interval would be a) wider b) narrower c) the same d) 42

wider