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.

Related Questions

Each of the question below consists of a question and three statements number I, II and III given below it. You have to decide whether the data provided in the statement are sufficient to answer the question. If the bus is travelling from Surat to Ahmadabad and a car is travelling from Ahmadabad to Surat, then what is the distance between Surat and Ahmadabad? I. The speed of a car is 40% less than the speed of bus. Bus started at 9 am and car started at 10 am and they meet at 3 pm of the same day. II. After travelling for 1 hour, because of traffic average speed of bus is decreased by 20% and covers distance between Surat to Ahmadabad in 11 hours. Original speed of car is 20% less than original speed of bus and before crossing bus it covered 200 km if starts 1 hour later than bus. After crossing car, bus covers remaining distance in 5 hours. III. Speed of bus is 10 km/hr more than the speed of car and before crossing car ratio of distances covered bus and car in same time was 5 : 4. Time taken by car to cover the distance between Ahmadabad and Surat is 2 hours 15 minutes more than time taken by bus to cover the same distance.