In a sample of defective tires, 72 have defects in materials, 99 have defects in workmanship, and 17 have defects of both types. How many tires are in the sample?
A) 154
B) 137
C) 171
D) 188
E) 44

Question

Quizplus · Accepted Answer

To find the total number of defective tires, we use the principle of inclusion-exclusion. We add the tires with material defects (72) and workmanship defects (99) then subtract the tires that have both defects (17) to avoid double-counting. So, the total is 72 + 99 - 17 = 154.

In a Sample of Defective Tires, 72 Have Defects in Materials