A study is going to be conducted in which a mean of a lifetime of batteries produced by a certain method will be estimated using a 90% confidence interval.The estimate needs to be within +/- 2 hours of the actual population mean.The population standard deviation is estimated to be around 25.The necessary sample size should be at least _______.
A) 100
B) 21
C) 923
D) 35
E) 423

Question

Quizplus · Accepted Answer

To find the sample size, use the formula for the confidence interval: n = (Z*σ/E)^2. For a 90% confidence interval, Z is approximately 1.645. Plugging in the values: n = (1.645*25/2)^2 ≈ 423.

A Study Is Going to Be Conducted in Which a Mean