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To reduce the usual time taken to cover a distance of 300 km by 1 hour, the speed of a bus is increased…

The correct choice is: 50 \[\frac{300}{v}-\frac{300}{v+10}=1\Rightarrow v(v+10)=3000\Rightarrow v^2+10v-3000=0\] \((v+60)(v-50)=0\Rightarrow v=50\) km/h (check: 6 h vs 5 h).…

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To reduce the usual time taken to cover a distance of 300 km by 1 hour, the speed of a bus is increased by 10 km/h. The usual speed of the bus (in km/h) is :

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Correct answer D

The correct choice is: 50

300v−300v+10=1⇒v(v+10)=3000⇒v2+10v−3000=0\frac{300}{v}-\frac{300}{v+10}=1\Rightarrow v(v+10)=3000\Rightarrow v^2+10v-3000=0

(v+60)(v−50)=0⇒v=50(v+60)(v-50)=0\Rightarrow v=50 km/h (check: 6 h vs 5 h).

Hence the answer is 50.

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  • NCHM Joint Entrance Examination (NCHM JEE)

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