Business Stat homework help
A manufacturer of cordless electric shavers sampled 13 from a day's production and found the mean time of continuous usage without recharging to be 410 minutes with a sample standard deviation of 30 minutes. We can assume that times are normally distributed. We wish to test if the true mean operating time without recharging is more than 400 minutes.
1. State the null and alternative hypotheses
2. The correct conclusion at the 0.05 level of significance is
I. Reject the null hypothesis
II. Do not reject the null hypothesis
III. Evidence suggests that the mean operating time is more than 400 minutes.
A. III
B. II
C. I and III
D. II and III
E. I
3. The correct calculated value of the test statistic is
A. -1.20
B. 1.20
C. 2.79
D. -2.52
E. -0.333
Please explain how you got the answers.