Question

019. 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%
оооо
(c) 60%
(d) 70%​

Answer 1

a) 80%


As 20% from car, 50% from bus and 10% by both car and bus
20+50+10 = 80%

Answer 2

Let X be the total population of the city.

P(car)=20×X ÷ 100= X/5

P(bus)=50×X ÷ 100=X/2

P(car ∩ bus)=10× X ÷ 100=X/10

P(car ∪ bus)=P(car)+P(bus)-P(car ∩ bus)

                   =X/5+X/2-X/10

                   = 3X/5

If X=100

then, 3×X = 3×100=3×20= 60%

            5        5