# Probability Problem - Standard Deviation

Calls to a customer service center last on average 2.7 minutes with a standard deviation of 1.4 minutes. An operator in the call center is required to answer 74 calls each day. Assume the call times are independent.

What is the standard deviation of the total amount of time in minutes the operator will spend on the calls each day? Give your answer to four decimal places.

I initially attempted to do: 74*1.4=103.6

However, this doesn't seem to work. I'm not exactly sure how to go about solving this problem.

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## 1 Answer

Hint: the variance, not the standard deviation, increases linearly with the number of calls (under the assumptions that you are expected to work under, especially independent variation from one call to another.)

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