A manager sample the receipts of every fifth person who goes through the line. Out of 50 people, 4 had a mispriced item. If 600 people go to this store each day, how many people would you expect to have a mispriced item?

The answer is 48.

Out of 50 people, 4 had a mispriced item: 50 people - 4 mispriced

Out of 600 people, x will have a mispriced item: 600 people - x

Make a proportion:

50 : 4 = 600 : x

50 * x = 4 * 600

50x = 2400

x = 2400 / 50

x = 48