Question

A recent national survey found that high school students watched an average (mean) of 7.2 DVDs per month with a population standard deviation of 0.90 hour. The distribution of DVDs watched per month follows the normal distribution. A random sample of 35 college students revealed that the mean number of DVDs watched last month was 6.20. At the 0.05 significance level, can we conclude that college students watch fewer DVDs a month than high school students?

b. State the decision rule. Multiple Choice

Reject H1 if z < -1.645

Reject H1 if z > -1.645

Reject H0 if z > -1.645

Reject H0 if z < -1.645

A recent national survey found that high school students watched an average (mean) of 7.2 DVDs per month with a population standard deviation of 0.90 hour. The distribution of DVDs watched per month follows the normal distribution. A random sample of 35 college students revealed that the mean number of DVDs watched last month was 6.20. At the 0.05 significance level, can we conclude that college students watch fewer DVDs a month than high school students?

c.	Compute the value of the test statistic. (Negative amount should be indicated by a minus sign. Round your answer to 2 decimal places.)

Value of the test statistic

Answer 1

Solution :

This is the left tailed test .

The null and alternative hypothesis is ,

H₀ :   = 7.2

H_a : < 7.2

Z _0.05 = -1.645

Reject H0 .z < -1.645

Test statistic = z

= ( - ) / / n

= (6.20 - 7.2) / 0.90 / 35

= -6.57