Question

On a track of 235km, bus travels the first 60km at a uniform speed of 40km/h. How fast the bus should travel the next 175km so as to get the average speed of 47km/h for the entire trip.  ​

Answer 1

Answer:-

Given:

Length of the track = distance travelled by the bus = 235 km.

Average speed of the bus = 47 km/h

It travels first 60 km with a speed of 40 km/h.

We know that,

Time = Distance/speed

→ Time taken by the bus = 60/40 = 3/2 hrs.

Similarly , let the speed of the bus to travel next 175 km be x km/h.

→ Time taken to travel next 175 km = (175/x) hrs.

We know that,

Average speed = Total Distance travelled/total Time taken.

• Total distance travelled = 235 km.

• Total Time taken = (3/2 + 175/x ) hrs.

• Average speed = 47 km/hr.

Hence,

→ 47 = 235 / [ 3/2 + 175/x ]

→ 47 = 235 / [ (3x + 350)/2x ]

→ 47 = 235 * (2x/3x + 350)

→ 47 (3x + 350) = 470x

→ 141x + 16450 = 470x

→ 16450 = 470x - 141x

→ 16450 = 329x

→ 50 km/h = x

Therefore, the bus has to travel with a speed of 50 km/h to make the Average speed of 47 km/hr for the whole trip.