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
Let
\[ n(C)=20\% \]
\[ n(B)=50\% \]
\[ n(C\cap B)=10\% \]
Using the formula,
\[ n(C\cup B)=n(C)+n(B)-n(C\cap B) \]
\[ =20\%+50\%-10\% \]
\[ =60\% \]
Answer
\[ \boxed{60\%} \]
Correct option: (c)