QUESTION 19

Which statementabout p-value is correct?

	A.	When calculating p-value, we assume the alternative hypothesis is true.
	B.	If the p-value is small,it would be likely to observe the data if the null hypothesis were true.
	C.	p-value is calculated from the data.
	D.	p-value can be used to construct confidence interval.

QUESTION 20

A poll by the National Sleep Foundation found that college students on average sleep about 7 hours per night. A sample of 169 college students yielded an average of 6.88 hours, with a standard deviation of 0.94 hours. Assuming that this is a random sample representative of all college students, a hypothesis test at significance level 0.05 was conducted to evaluate if college students on average sleep less than 7 hours per night. The p-value for this hypothesis test is 0.0485. Which of the following is the correct interpretation of this p-value

	A.	The probability that students on average sleep less than 7 hours per night.
	B.	The probability that students on average sleep less than 7 hours per night, if in fact a random sample of 169 students yields an average of 6.88 hours or less
	C.	The probability that students on average sleep less than 7 hours per night, if in fact a random sample of 169 students yields an average of 6.88 hours or less
	D.	The probability that a random sample of 169 students on average sleep 6.88 hours or less per night, if in fact students on average sleep 7 hours per night.

QUESTION 21

Which statement about correlationcoefficient is true?

	A.	Correlation coefficient can measure any relationships between two variables.
	B.	Correlation coefficient can only be a positive value.
	C.	Correlation coefficients can measure casuality.
	D.	Correlation coefficient can beaffected by outliers.

QUESTION 22

Which statement is not true about confidence interval?

	A.	Given the same confidence level, a wider interval is less precise
	B.	In practice, we want the confidence interval to be relatively narrow givena fixed confidence leve.
	C.	The width of a confidence interval is determined by the sample size.
	D.	The width of a confidence interval is determined by the sample mean

QUESTION 23

In testing for the differences between the means of 2 independent populations where the variances in each population are unknown but assumed equal,what are the degrees of freedom?we know their sample sizes are 10 and 12, respectively.

	A.	20
	B.	21
	C.	22
	D.	23

QUESTION 24

The owner of Get-A-Away Travel has recently surveyed a random sample of 305 customers to determine whether the mean age of the agency's customers is over 32. The hypotheses are 0: = 32,a: > 32. If he concludes the mean age is over 32 when it is actually not, he makes a ______ error

	A.	Type I
	B.	Type II
	C.	Silly
	D.	No