Question 79

A plane left 30 minutes later than the scheduled time and in order to reach the destination 1500 km away in time, it had to increase the speed by 250 km/hr from the usual speed. Its usual speed is:

Solution

The plane left half an hour late i.e it had to cover the same distance in half hour less time.
Now, we know that time = distance/speed
Let the origibal speed of the plane be x.
Now, (1500/x - 1500/x+250) = 0.5
Solving we get x = 750 km/hr.
Hence, the correct answer is option D.
 


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