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42 km in 1 hour 40 min 48 sec. What is the usual speed of the car?A car travelling with 5 of its usual speed covers 7
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17 6 km/hr 7 - 35 km/hr
- 25 km/hr
- 30 km/hr
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Correct Option: B
1 hr 40 min 48 sec
| = 1 hr |  | 40 + |  | min | |
| 60 |
| = 1 hr | | 40 + | | min | |
| 5 |
| = 1 hr | min | |
| 5 |
| = | | 1 + | | hr | |
| 300 |
| = | hr | |
| 300 |
| ∴ Speed = | |||||
| 300 | |||||
= 25 kmph
| Now, | ×usual speed = 25 | |
| 7 |
| ∴ Usual speed = | |
| 5 |
= 35 kmph
