Question

A worker in a factory made a table to show the total number of tires made during each of the first 3 hours one day. In the table below, she also recorded the number of defective tires for each hourly batch.

The factory makes 150 tires in 1 hour of which 8 tires are defective. In 2 hours, the factory makes 175 tires of which 3 tires are defective. In 3 hours, the factory makes 125 tires of which 4 tires are defective.

The factory makes a total of 1,200 tires during the 8-hour workday. Based on the data in the table, how many of the tires are defective?

A.
15 tires

B.
36 tires

C.
40 tires

D.
64 tires

Answer 1

First 3 hours: total tires = 150 + 175 + 125 = 450, defects = 8 + 3 + 4 = 15.
Defect rate = 15/450 = 1/30. For 1,200 tires expected defects = 1200*(1/30) = 40.

Answer: C. 40 tires.