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A train covers a distance of 10 km in 12 minutes. If its speed is decreased by 5 km/hr, the time taken by it to cover the same distance is equal to
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- 40 minutes
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40 minutes 3 - 20 minutes
- 15 minutes
Correct Option: B
Time = 12 minutes
| = | hour = | hour | ||
| 60 | 5 |
| Speed of train = | ||
| 5 | ||
= 50 kmph
New speed = 50 – 5 = 45 kmph
| ∴ Required time = | |
| Speed |
| = | = | hour | ||
| 45 | 9 |
| = |  | × 60 |  | minutes | |
| 9 |
| = | minutes | |
| 3 |
Second Method :
| Here, S1 = | km/min | |
| 12 |
| = | × 60km/hr | |
| 12 |
| = 50 km/hr, t1 = | = | hr | ||
| 60 | 5 |
S2 = 45 km/hr, t2 = ?
S1t1 = S2t2
| 50 × | = 45 × t2 | |
| 5 |
| t2 = | × 60 min | |
| 45 |
| = | min | |
| 3 |
