On a journey, across Bangalore, a cab averages 12 kmph for 60% of the distance, 15 kmph for 20% of i

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19 Jun 2019 Speed

On a journey, across Bangalore, a cab averages 12 kmph for 60% of the distance, 15 kmph for 20% of it and 30kmph for the remainder. The average speed for the whole journey is :

OPtion

1) 13.50
2) 14.70
3) 14.80
4) 15.50
5) 14.45
6) 14.29
7) 15.50
8) 15.70
9) 15.29
10) None of these

Solution

Lets assume that total distance is 100 KMs

So for 60 KMS time take = 60/12 = 5 Hours
For 20 KMS time take = 20/15 = 4/3 hours
For remainder 20 KMS time take = 20/30 = 2/3 hours

Total Time taken = 5 + 4/3 + 2/3 = 7 hours

Average speed = 100/7 = 14.29 KMPH

Correct Option: 6 Best Solution (4)