An information technology (IT) manager wants to estimate the average amount of time that employees in her organization spend reading, deleting or otherwise dealing with "spam" (unsolicited e-mail) on a daily basis. She randomly selects 42 employees and records the amount of time they spend on spam throughout a given day. Assume that the true population of time spent on spam is normal with a mean of 25 minutes and a standard deviation of 3.5 minutes.

What is the standard deviation of the sample mean (i.e., the standard error)? Give your answer to 2 decimal places

Please show how to find answer in excel