Last month, customers at a gift shop bought 40 birthday cards,
19 congratulations cards, 20 holiday cards, and 21 thank you
cards. Suppose 125 customers buy greeting cards next month.
How many would you expect to buy a birthday card?
I put 40 (Number of birthday cards bought previously) over 125 (Number of expected costumers) and multiplied it by 100 (Total number of card bought previously) to get my answer. Hopefully that helps :)
