Question

On a 60 km stretch of road, a cyclist travels first 20 km at a uniform speed of 20 km/hr. how fast must he travel the remaining distance so that his average speed is 10 km/hr for the entire trip.

Answer 1

Step-by-step explanation:

Given:

• Total distance =60km
• Average speed of entire journey=20km/h
• Total Time taken = total distance/average
• speed =60/10 =6hr

Case :1

Let us CALCULATE

time taken to cover first 20km

Speed=20km/h

Distance=20km

T=distance/ speed=20/20 =1hr -equation ( 1)

Case: 2

Let speed be =Xkm/h

X=40 KM/t t=40/X hours ----equation( 2)

Total time = add equation 1 and 2

=1 +40/X

Since total time =3 h

6 =1 +40/X

6-1 =40/X

5 =40/X

X=8 km/h

Therefore cyclist should travel next 40 km distance at a speed of 8 km/h.