Question

A boy is cycling along a square field at the speed of 18 km/hr. In how much time will he complete 5 rounds if the area of squre field is 9604m square?

Answer 1

$area \: of \: square \: = \: 9604 \: {m}^{2} \\ side \: of \: that \: square \: = \: \sqrt{9604} = 98 \\ perimeter \: of \: square \: = \: 4 \times 98 = 382 \: metres \\ changing \: \frac{km}{hr} \: to \: \frac{m}{s} \\ \frac{18}{1} \times \frac{5}{18} = \frac{5m}{s} \\ 1 \: round = 382 \: metres \\ 5 \: rounds = 382 \times 5 \: metres \\ 1910 \: metres \\ time \: taken \: = \frac{distance}{speed} \\ time \: taken \: = \frac{1910}{5} \\ time \: taken \: = 382 \: seconds \\ 382 \: seconds = 6 \: minutes \: 22 \: seconds.$