Question

A person goes to his office by scooter at the speed of 50 km/hr and reaches 10 minutes earlier. If he goes at the speed 40 km/hr, then he reaches 20 minutes late. What will be the speed (in km/hr) of the scooter to reach on time?

Answer 1

Ans: 24 kmph

Let the distance to office be

x

km

Time taken if he rides at 20 kmph =

x

20

hr

Time taken if he rides at 30 kmph =

x

30

hr

Difference of time = 10 min + 10 min = 20 min =

1

3

hr

x

20

−

x

30

=

1

3

3

x

−

2

x

=

20

x

=

20

i.e., Distance to office = 20 km

Time taken if he rides at 20 kmph =

20

20

= 1 hr

if he rides at 20 kmph, he will reach office 10 minutes late

Therefore, to reach office just in time, he should reach in 50 minutes (or 5/6 hour)

Required speed =

20

(

5

6

)

=

20

×

6

5

=

24