Question 1

A study is undertaken to test the emission levels of minivans. At the outset, a research hypothesis is established that states more than 75% of minivans meet emission standards (Null hypothesis is that 75% meet the standard). An alpha value of 0.05 is chosen. A sample of 180 minivans is then selected.Of these cars, 130 cars met the standard. What conclusion can be reached about the null hypothesis?

Question 2

A research group would like to conduct a mental health study in a small town to determine the mean number of people who have had mental health issues in their life.The error in estimating the mean is to be less than 8% with a 98% level of confidence.No estimate of the population proportion exists.What is the size of the sample needed for this study?

Question 3

A nationwide survey of university students was conducted and found that students spend two hours per class hour studying. A professor at your school wants to determine whether the time students spend studying at your school is different from the two-hour average. A random sample of fifteen statistics students is carried out and the findings indicate an average of 1.75 hours with a standard deviation of 0.24 hours.What is the hypothesis used for the case?

H0 ism2; H1 is m = 2

H0 is m = 2; H1 is m 2

H0 is m = 2; H1 is m < 2

H0 is m < 2; H1 is m > 2

Question 4

i. An alternate hypothesis is a statement about a population parameter that is accepted when the null hypothesis is rejected.

ii. The level of significance is the risk we assume of rejecting the null hypothesis when it is actually true.

iii. There is only one level of significance that is applied to all studies involving sampling.

(i) and (ii) are correct statements but not (iii).

(i) is a correct statement but not (ii) or (iii).

(i), (ii), and (iii) are all correct statements.

(i) and (iii) are correct statements but not (ii).

Question 5

How would you narrow the width of a confidence interval estimate without changing the level of confidence attached to the answer?

Increase the population mean

Decrease the standard deviation

Increase the variance

Decrease the sample size

Question 6

Sampling error is the difference between a corresponding sample statistic and its

sample mean

biased sample

chance error

population parameter

Question 7

A research group would like to conduct a mental health study in a small town to determine the mean number of people who have had mental health issues in their life.The error in estimating the mean is to be less than 60 with a 90% level of confidence.The research group found a report conducted on the residents of a nearby town that estimated the standard deviation to be 480 people.What is the required sample size?

174

176

173

175

Question 8

What does the central limit theorem tell us about the mean of a large sample?

Ifthe population is skewed, then for more than 10 sample size the sampling distribution of sample mean will be normal.

Ifthe population is not symmetric, then for more than 20 sample size the sampling distribution of sample mean will be normal

Ifthe population is normal distribution, then for any sample size the sampling distribution of sample mean will be normal.

At least 30 samples are randomly collected.

Question 9

What do we call the statement that determines if the null hypothesis is rejected?

Alternate hypothesis

Test statistic

Critical value

Decision rule

Question 10

How many recent LU graduates should be interviewed if the university wishes to estimate the mean salary of students coming out of their programs? Assume the estimate is to be accurate within 2 thousand dollars, 19 times out of 20, and that previous studies of recent graduates have found a standard deviation of 10 thousand dollars.

97

95

96

98