Question

a man runs round a cirvular field of radius 50 m at a speed of 12km/hour .what time is taken by the man to take 20 rounds of the field​

Answer 1

Circumfernce of circle = 2*22/7*50

=314.28 (area to be covered in 1 round)

for w0 rounds =314.28×20

=6285.6

S=D/T

Speed= 12×5/18(in metre /sec)

=10/3

Time= distance /speed

6285.6/3.333

=1885.86 sec

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Answer 2

Answer:

$\large\boxed{\sf{31.4\;\;min}}$

Step-by-step explanation:

Radius of Circular field, r = 50 m

.°. Circumference , c = 2πr = 100π m

Speed , v = 12 km/hr = 12×5/18 = 10/3 m/s

Distance covered in one round = c = 100π m

.°. Distance in 20 rounds =20×100π =2000π m

Time taken, t = Distance/Speed

$= \dfrac{2000\pi}{ \frac{10}{3} } \\ \\ = \frac{2000\pi \times 3}{10} \\ \\ = 200\pi \times 3 \\ \\ = 600\pi \\ \\ = 600 \times \frac{22}{7} \\ \\ = \sf{1885.71 \: \: \: sec.}$

Time in minutes = t/60

$= \frac{600 \times 22}{60 \times 7} \\ \\ = \frac{10 \times 22}{7} \\ \\ = \sf{31.4 \: \: min}$