Question

A dean of a business school is interested in determining whether the mean grade point average (GPA) of students is different from 3.04. The population standard deviation is 0.41. A random sample of 200 students indicates a sample mean GPA of 2.94. A test is conducted at the 0.05 level of significance to determine whether the mean grade point average (GPA) of students is different from 3.04. What is the test statistic value in this test?

Select one:

a. -0.244

b. -3.449

c. +3.449

d. +0.244

A researcher reported that the 95% confidence interval for the mean ranged from 460 to 540. He knew that the population is normally distributed. He was sure that the mean of the sample was 500, the standard deviation of the sample was 160. The reported confidence interval may be interpreted as:

Select one:

a. None of the other choices

b. The chance that the population mean equals to the sample mean is 95%.

c. We are 95% confident that the population mean is between 460 and 540.

d. 95% of the sample means are between 460 and 540.

According to a poll on customer behavior, 30% of people say they will only consider cars manufactured in their country when purchasing a new car. Suppose you select a random sample of 180 respondents. The probability is 80% that the sample percentage will be contained within what symmetrical limits of the population percentage?

Select one:

a. 23.3% and 36.7%

b. 24.4% and 35.6%

c. 25.6% and 34.4%

d. 27.1% and 32.9%

The following table shows the number of weekly traffic accidents occurred on a bridge in a sample during a particular year.

Number of Weekly Accidents	0	1	2	3	4	5
Number of Weeks	8	13	12	4	2	1

Find the mean number of weekly accidents.

Select one:

a. 8

b. 2

c. 6.67

d. 1.55

Answer 1

1 ) Define , : Population mean of the grade point average (GPA) of students

To test :

Test statistic :

where ,

The value of the test statistic :

2 )  c. We are 95% confident that the population mean is between 460 and 540.

The correct option is ( c ) .

3 ) Upper bound =

Lower bound =

where , and

The correct option is ( c )

4 ) The frequency distribution table is given below :

X ( xi )	Frequency ( fi )
0	8
1	13
2	12
3	4
4	2
5	1
Total	40

Mean :

The correct option is ( d ) .