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? d. What is your decision regarding H0?

Multiple Choice

Cannot reject

H0 Reject H0

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

P(z < -.57) = 0

P-value = 0

= 0.05

P-value <

Reject the null hypothesis (H0)