Question

The area of a circlular field is 154 sq.m find the time taken by an athlate to complete 2rounds if she is jogging at the rate of 5 km/hr

Answer 1

A = πr^2 = 154
r =7
2πr = 14π
for 2 rounds distance = 28π
speed 5km/hr
time =distance /speed
T= 28π/5 will be in hours

Answer 2

Area of the circle =
$154 \: {m}^{2} = \pi {r}^{2}$
So
$154 = \frac{22}{7} \times {r}^{2}$
calculating Radius
${r}^{2} = \sqrt{49 } \\ r = 7 \\ so \: we \: got \: the \: radius \: = 7$
circumference=
$2\pi \: r = 2 \times \frac{22}{7} \times 7 = 44 \\ so \: the \: distance \: for \: one \: round = 44 \\ for \: 2 \: rounds \: distance = 2 \times 44 = 88 \: m$
we know that
$time = \frac{distance}{speed } \\ hence \: total \: time \: taken \: = \frac{88}{5000} hr \\ = \frac{11}{625} hr$

hope this helps you
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