One step in the manufacture of a certain metal clamp involves the drilling of four holes. In a sample of 150 clamps, the average time needed to complete this step was 72 seconds and the standard deviation was 10 seconds.
a. Find a 95% con?dence interval for the mean time needed to complete the step.
b. Find a 99.5% con?dence interval for the mean time needed to complete the step.
c. What is the con?dence level of the interval (71, 73)?
d. How many clamps must be sampled so that a 95% con?dence interval speci?es the mean to within $1.5 seconds?
e. How many clamps must be sampled so that a 99.5% con?dence interval speci?es the mean to within :15 seconds?

Answer rating: 100% (QA)

a To find a 95 confidence interval set 1 a 095 to obtain a 005 and a2 0025 We then ... View the full answer