a bike drive from a to b at a speed of 30 kilometre per hour and returns to a at the speed of 20 kilometre per hour find average speed
Answers
Answered by
8
let a - b distance be d
for 1st trip,
speed = distance/time
30 = d/t1
hence, t1 = d/30
for 2nd trip,
speed = distance/time
20 = d/t2
hence, t2 = d/20
total time = t1 + t2
= d/30 + d/20
= d (1/20 + 1/30) [took d common]
= d (20 + 30/20*30)
= d (50/600)
= d (1/12)
speed average = total distance/total time
= 2d/ [d(1/12)]
= 2/ (1/12)
= 24 km/hr
Hence, average speed of the car will be 24 km/hr.
hope it helps...
Answered by
4
- Given to find it's average speed....
- So, it's average speed = Total distance travelled by total time taken .
Total distance travelled is 20+30 km
time taken is 2 hours .....
- it's average speed =50/2 Km/h
- 25 km/h
it's average speed is 25km/hr
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