Question

solve the following:-

a person swims 100 M in the first 48, ATM in the next 48 and 45m in the last 20 years. what is the average speed?

Answer 1

In this question Distance is constant .only speed and time varies. So in this type we use basic identity of formula of time and Distance keeping one identity which is distance constant.

S=D/T

S is indirectly proportion to T ( keep D constant)

Given data -

S1 = 2.5km /h

S2= 4.5km/h ( 2km increase speed so 2.5+2=4.5)

S1/S2= 2.5/4.5= 5/9

Therefore

T2/T1= 9/5 ( because S is indirectly proportion to T))

The reverse of speed is time taken

So T2 -T1 = 9–5 = 4unit

These 4unit = 16mint ( 16mint =6mint+10mint, time gap)

1unit = 4mint

So Time taken by T2 = 9unit = 9×4= 36mint ( convert 36mint into hour =36/60 hr )

So, Distance =speed ×time

Distance = 2.5Km/h × 36/60 hour = 1.5Km

Hope this unit method help you . With this method you can finish question in 5sec. Best of luck . Keep learning keep growing