Question

If a person has to drive 210 km, how
long will the journey take if he drives
at an average speed of 20 km/hr for
120 km and at an average speed of
30 km/hr for 90 km, and have a
60 minutes stop for refreshments
midway through the journey?

Answer 1

In first case
speed =20km/h
distance=120 km
s=d/t
20=120/t
t=6h
In second case
speed=30km/h
distance=90km
s=d/t
30 =90/t
t=3 h
Total time taken =6+3+1=10hours

Answer 2

journey will  take 10 hrs

Step-by-step explanation:

an average speed of 20 km/hr for 120 km

Time = Distance /Speed

=> Time = 120/20

=> Time = 6 hrs

an average speed of 30 km/hr for 90 km

=> Time =90/30

=> Time = 3 hrs

Stop time for refreshment = 60 Mins =  1 Hr

Total Time = 6 + 3 + 1  = 10 hrs

journey will  take 10 hrs

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