Question

a man runs around field of radius 50 m at a speed of 12 km/hr what time is taken by the man to make 20 rounds of field
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Answer 1

Answer:

10π minutes

Step-by-step explanation:

First of all we have to find the circumference of the field and that would be 2πr.

2πr=2π×50=100π

So,the circumference of the field would be 100π metres.

Now to find the answer our first approach should be towards what to find next. As we know that Time=Distance/Speed,so we should find the total distance covered so as to find the time.

Total distance covered=20×100π(as the man took 20 rounds of the field) which would be equal to 2000π metres.

Now we have all the values to find the time taken,so now we have to put those values in the above formula. But first we have to convert 2000π metres into kilometres as speed is also given in kilometre.

1000m=1km so,

2000m=2km

Putting the values in the above formula we get,

Time=2π/12 hours = π/6 hours

Now 1 hour = 60 minutes,so we multiply the above answer by 60.

(π/6)×60 = 10π minutes or 220/7 minutes or

31.428 minutes.

Hope this helps you.