# How many newspapers should the newsstand operator order to ensure that he runs short on no more than 20% of days?The demand for a daily newspaper at a newsstand at a busy intersection is known to...

How many newspapers should the newsstand operator order to ensure that he runs short on no more than 20% of days?

The demand for a daily newspaper at a newsstand at a busy intersection is known to be normally distributed with a mean of 150 and a standard deviation of 25.

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### 1 Answer

The demand for a normal newspaper at a newsstand has a mean of 150 and a standard deviation of 25. As the demand is normally distributed a normal table can be used.

The papers can run short on a maximum 20% of days.

Using the table given below, the z-score for 0.8 is 0.84

0.84 = (N - 150)/25

=> N = 171

**The newspaper vendor should order a minimum 171 newspapers to ensure that he runs low on no more than 20% of the days.**