Question

A rectangular field is 72 m by 58 m. Amar walks around it at a rate of 3 km per hour. What time will he take in taking 2 rounds?

Answer 1

Hint: Amar walks around the rectangular field so we have to find the perimeter of the field first and then, to find the total distance travelled, multiply the perimeter by 2. Apply distance, speed and time formula to calculate time.

Complete step-by-step answer:
Given, rectangular field is 72 m by 58 m.

Therefore, perimeter of rectangular field = 2(l + b) = 2(72 + 58) m = 260 m.
Distance covered by Amar in 1 round is equal to the perimeter of the rectangle.
Now it is also given that Amar walks around the rectangular field so it covers 260 m in one round.
Therefore, the total distance covered by Amar in 2 rounds = 2 x 260 m = 520 m.
Also we have, Distance = Speed × Time
Speed of Amar = 3 km/h =\[3 \times \dfrac{{1000}}{{3600}}\] m/s {1 km = 1000 m and 1 h = 3600 s}
                                              = $\dfrac{5}{6}$m/s
Thus, we can say that Amar covers $\dfrac{5}{6}$ meter in 1 second
Therefore, he covers 520 m in $\dfrac{{560}}{{\dfrac{5}{6}}}$ second = $\dfrac{{560 \times 6}}{5}$s = $424$ s =$\dfrac{{424}}{{60}}$minutes = $10.4$ minutes {1 minute = 60 second)

Therefore, the total time Amar takes is 10.4 minutes.

Note: To solve this type of problem we should know the figure and formulae of the rectangle. We should know the relation between distance speed and time and also the relations between second, minute and hour. Always draw figures based on statements given in question to understand the problem clearly. Here by drawing the rectangle we have understood, we need to find the perimeter of the rectangle to get the result. While substituting the quantities make sure that all the quantities are in the same units.