In a sample of 60 electric motors, the average efficiency (in percent) was 85 and the standard

Question:

In a sample of 60 electric motors, the average efficiency (in percent) was 85 and the standard deviation was 2.

a. Find a 95% confidence interval for the mean efficiency.

b. Find a 99.5% confidence interval for the mean efficiency.

c. What is the confidence level of the interval (84.63, 85.37)?

d. How many thermostats must be sampled so that a 95% confidence interval specifies the mean to within ±0.35?

e. How many thermostats must be sampled so that a 99.5% confidence interval specifies the mean to within ±0.35?

Fantastic news! We've Found the answer you've been seeking!

Step by Step Answer:

Related Book For  book-img-for-question
Question Posted: