Question

A man covers 60 km distance with speed of 10, 12 and 15 kmph on three successive days. Find average speed.

Answer 1

Answer:

15

Step-by-step explanation:

60/10+60/12+60/15

=6+5+4

=15km/hr

Answer 2

GIVEN

The distance in all three cases are equal

d1 = d2 = d3 = 60km

Speeds taken by Man is ,

10km/hr, 12km/hr & 15km/hr

TO FIND

Average Speed

SOLUTION

Av.Speed = Total Distance ÷ Total Time

Let T1, T2 and T3 be time taken for different speeds,

Now,

Time = Distance/Speed

=> T1 = D1/S1= 60/10 = 6hr

=> T2 = D2/S2=60/12 = 5hr

=> T3 = D3/S3=60/15 = 4hr

Average speed =

(D1+D2+D3)/(T1+T2+T3)

=(3 × D) ÷ (6+5+4)

=( 3 × 60 )/ 15

= 180 / 15

= 12kmph

Hence the average speed is 12km/hr.