Correct Answer - Option 3 : 9 m
Given:
Two people are cycling at a speed of 10.8 km/hr and 12 km/hr, and in the same direction, a bus is also traveling. The bus crosses two people in 9 and 13.5 seconds.
Formula used:
Speed = Distance/ Time
Calculation:
Let us assume the speed of the Bus = B km/hr, L m be the length of the bus.
Now the distance traveled by two people while Bus crosses them is the length of the Bus.
⇒ (L) m = (B – 10.8) × 9 × 5/18 = (B – 12) × 13.5 × 5/18
⇒ (B – 10.8) × 9 = (B – 12)× 13.5
⇒ 2× (B – 10.8) = 3× (B – 12)
⇒ 2B – 21.6 = 3B – 36
⇒ 36 – 21.6 = 3B – 2B
⇒ B = 14.4 Km/hr
Now the length of the bus L m will be
∴ (14.4 – 12) × 13.5 × 5/18 = 9 m