Standard deviation of a shop's daily pizza output

Question

A pizzeria employs $25$ workers whose daily outputs are independent, and each worker's output has a standard deviation of $60$ pizzas. What is the standard deviation of the shop's total daily output?

Short answer

$300$ . Variances of independent quantities add: $25\cdot60^2$ . Taking the square root gives $5\cdot60=300$ .

Adapted from QuantQuestions.io; question and answer rewritten by SelfMadeQuant.com.

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Lessons behind this question

Expectation, Mean, and Variance
Independence
Conditional Expectation and Variance Revisited

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