A bus moves from station A towards station B, which is at a distance of 189 km. An hour later, a car, the ratio of whose speed with the bus is 3 ∶ 2, starts from station A and moves towards station B. Find the speed of the bus (in km/h), if the car arrives at station B in half an hour earlier than the bus.
A bus moves from station A towards station B, which is at a distance of 189 km. An hour later, a car, the ratio of whose speed with the bus is 3 ∶ 2, starts from station A and moves towards station B. Find the speed of the bus (in km/h), if the car arrives at station B in half an hour earlier than the bus. Correct Answer 42
Given:
Distance = 189 km
The ratio of the speed of car and bus = 3 : 2
Concept used:
When the distance is constant, then speed is inversely proportional to time
Formula used:
Speed = Distance/Time
Calculation:
The ratio of speed of car and bus be 3x and 2x respectively
When the distance is constant, then speed is inversely proportional to time
So,
The ratio of time of car and bus be 2x and 3x respectively
Now,
The difference between the time of bus and car = (3x – 2x) = 1x
According to the question
Total time taken by car = (60 min + 30 min) = 90 min
⇒ (90/60) = 3/2 hr
Time taken by bus = (3 × 3/2) = 9/2 = 4.5 hr
Now,
Speed = 189/4.5
⇒ 42 km/h
∴ The speed of the bus is 42 km/h
Confusing point:
Time taken by car to move from station A to station B firstly by one hour and then extra half an hour.