Question:
In a city 20% of the population travels by car, 50% travels by bus and 10% travels by both car and bus. Then, persons travelling by car or bus is
(a) 80%
(b) 40%
(c) 60%
(d) 70%
Solution:
(c) 60%
Suppose C and B represents the population travel by car and Bus respectively.
$n(C \cup B)=n(C)+n(B)-n(B \cap C)$
$=0.20+0.50-0.10$
$=0.6$ or $60 \%$