Question

In a city, $20$ percent of the population travels by car, $50$ percent by bus and $10$ percent travels by both car and bus. Then person travelling by car or bus is

• A. $80\%$
• B. $40\%$
• C. $60\%$
• D. $70\%$

Answer 1

Answer: (C)

$60\%$

Answer 2

Let population be $100$. Let $A$ and $B$ be the sets consisting of population which travels by car and by bus respectively. $n(A) = 20$, $n(B) = 50$ and $n(B \cap A) = 10$ $n(A \cup B) = n(A) + n(B) - n(A \cap B)$ $= 20 + 50 - 10 = 60\%$.