Question

An employee sample estimated the standard deviation of emails received per day to be 155 emails. You are researching the average emails received per day. You want to know how many employees you should survey if you want to know, at a 90% confidence level, that the sample mean emails per day is within 47 emails of the true mean emails per day.

Use Excel to find the value for z you should use to calculate a 90% confidence level.

Round your answer to three decimal places.

Answer 1