A man travels 450 km, in which 150 km is covered by car, 100 km by bus and rest of the journey by train. If the average speed of man for the whole journey is 75 km/hr and the ratio of the speed of car, bus and train is 3 : 2 : 4, then find the time in which he can complete the journey by bus alone?

A man travels 450 km, in which 150 km is covered by car, 100 km by bus and rest of the journey by train. If the average speed of man for the whole journey is 75 km/hr and the ratio of the speed of car, bus and train is 3 : 2 : 4, then find the time in which he can complete the journey by bus alone? Correct Answer 9 hr

Given:

Total distance is 450 km 

Distance covered by car is 150 km

Distance covered by bus is 100 km

Ratio of speed of car, bus and train is 3 : 2 : 4

Average speed = 75 km/hr

Formula used:

Average speed = Total distance/total time

Time = Distance/speed

Calculation:

Let, D = Total distance

D1 = Distance covered by car

D2 = Distance covered by bus

D3 = Distance covered by train

S1 = Speed of car

S2 = Speed of bus

S3 = Speed of train

Since D = 450 km

So, D3 = D - (D1 + D2)

⇒ D3 = 450 - (150 + 100) km

⇒ D3 = 200 km

Let the speed of car be 3x, bus be 2x and train be 4x.

Since, Average speed = Total distance/total time

So, 450/(150/3x + 100/2x + 200/4x) = 75

⇒ 450/(50/x + 50/x + 50/x) = 75

⇒ 450/(150/x) = 75

⇒ 3x = 75

⇒ x = 25

So, S2 = 2x

⇒ S2 = 2 × 25 km/hr

⇒ S2 = 50 km/hr

Now, time taken by bus to complete journey is 450/50 hr

∴ Time takes taken by bus to complete journey is 9 hr.

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.