Question

2. A boy run for 10min at a uniform speed of 9km/h at what speed should he run for the next 20min so that the average speed comes to 12km/h?​

Answer 1

Answer:

At what speed should he Run for next 20 minutes so that the average speed comes to 12 km per hour. Given : Speed = s₁ = 9 km h⁻¹. Time = t₁ = 10 min = hrs

Explanation:

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Answer 2

Question:-

A boy run for 10min at a uniform speed of 9km/h at what speed should he run for the next 20min so that the average speed comes to 12km/h?

Given:-

t = 10minutes

u = 9km/h

v = 12 km/h

t = 20 minutes

speed = ?

Explanation:-

Average Speed = 12kmph

There are two times = 10 , 20

10+20 = 30 = 1/2 h

(Because all are in hour's so we have to change minutes to hour)

Average Speed = Total Distance covered

Total time taken

(Distance 1 + distance 2) ..........(1)

(Time 1 + time2)

Distance 1 = speed × time

9 × 1 .........(2)

6

3/2 km

Now,

D2 from 1 and 2

6 = (3/2 + 2d)

D2 = 9/2 kmph ......(3)

speed = distance 2

time 2

=(9/2)/(1/3)

= 13.5 kmph