Question

A man covers two-thirds of a distance at 4 kmph and the remaining at 5 kmph. If the total time taken be 42 minutes, find the total distance.​

Answer 1

Answer:

Now according to question

distance covered by 4km/h is 2/3x and 1/3x distance covered by 5km/h

we also know time=speed /distance

use this concept

4/(2x/3) +5/(x/3)=42/60 {because time given 42min , convert it hour I.e. 42/60hour}

=> 6/x+15/x=7/10

=> 21/x=7/10

=> x=30km

Answer 2

Let total distance be x.

Therefore

(2/3) x will be covered at 4kmph........... time(1) =((2/3)*x/4)hrs

(1/3) x will be covered at 5kmph........... time(2) =((1/3)*x/5) hrs

time(1) +time (2) = 42/60 hrs
(2x/12) + (x/15) = (7/10)
(7x/30)=(7/10)
x = 3 km