A train travelled at one-thirds of its usual speed, and hence reached the destination 30 minutes after the sch

Question

A train travelled at one-thirds of its usual speed, and hence reached the destination 30 minutes after the scheduled time. On its return journey, the train initially travelled at its usual speed for 5 minutes but then stopped for 4 minutes for an emergency. The percentage by which the train must now increase its usual speed so as to reach the destination at the scheduled time, is nearest to

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Accepted Answer

67. Let the total distance be 'D' km and the speed of the train be 's' kmph. The time taken to cover D at speed d is 't' hours. Based on the information: on equating the distance, we get s × t = s 3 × ( t + 1 2 ) s\ 	imes\ t\ =\ \frac{s}{3}	imes\ \left(t+\frac{1}{2}ight) s × t = 3 s ​ × ( t + 2 1 ​