Lifetime of electronics:In a simple random sample of100 electronic components produced by a certain method, the mean lifetime was125 hours. Assume that component lifetimes are normally distributed with population standard deviation= 20 hours. Round the critical value to no less than three decimal places.

(b) Find the sample size needed so that a95% confidence interval will have a margin of error of 4. A sample size ofis needed so that a95% confidence interval will have a margin of error of4. Round the sample size up to the nearest integer.