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A man covers one-third of his journey at 30 km per hr. and the remaining two-third at 45 km per hr. If the total journey is of 150 kms, what is his average speed for the whole journey?
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- 38 kmph
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38 4 kmph 7 - 64 kmph
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39 4 kmph 7
Correct Option: B
Length of journey = 150 kms
| rd of journey = | = 50 kms | ||
| 3 | 3 |
| Remaining | journey | |
| 3 |
= 150 – 50 = 100 kms
| Time taken in | rd journey at 30 km per hr. | |
| 3 |
| t1 = | = | hrs. | ||
| 30 | 3 |
| Time taken in | rd journey at 45 km per hr. | |
| 3 |
| t2 = | = | hrs. | ||
| 45 | 9 |
Total time taken in whole journey = t1 + t2
| = | + | = | = | hrs. | ||||
| 3 | 9 | 9 | 9 |
| Average Speed = | = | = | |||
| 35/9 | 35 | 7 |
| = 38 | km per hr. | |
| 7 |
