a cell phone company found that 15 of their phones sold in June were defective. The company sold 250 phone in June. How many of the 300 phones sold in July should they expect to be defective?
Write and solve an equation of ratios, as follows:
15 250
----- = ------- = 10/12.
x 300
Then 15(12) = 10x, and x = 18. The company could well predict that 18 out of the 300 phones it sells in July will be defective, based upon past history.
