Question

At a fast food restaurant, 51% of the customers order their food to go. In a sample of 300 customers, find the standard deviation of the number that order their food to go. (Round your answer to two places after the decimal point.)

Answer 1

The standard deviation of a number given a percentage is given as;

`\begin{gathered} S\mathrm{}D=\sqrt[]{npq} \\ \text{Where n= sample size} \\ p=\text{ percentage of the customers that order their food to go } \\ q=\text{ percentage of the customers that do not order their food to go} \\ q=1-p \end{gathered}`
`\begin{gathered} SD=\sqrt[]{300(0.51)(0.49)} \\ SD=\sqrt[]{74.97} \\ SD=8.66 \end{gathered}`

The standard deviation of the number that order their food to go is 8.66