Question

Jammutavi express leaves Jammu for Kanya Kumari
at 120 km/h and returns to Jammu at 80 km/h. What
is the average speed of the train during the whole
journey?
(a) 47.5 km/h
(b) 96 km/h
(c) 38 km/h
(d) 57.5 km/h​

Answer 1

Important Formula :

If a car covers a certain distance at  x  km/hr and an equal distance at  y  km/hr.

Then the average Speed of the whole journey = (2xy/x + y) km/hr.

Here,

It leaves at 120 km/hr and returns at 80 km/hr.

=> 2(120)(80)/(120 + 80)

=> 19200/200

=> 96 km/hr

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