Question

.The area of a rectangular field is 3584msq. and its length is 64m.A boy runs around the field at the rate of 8km/h.How much time will he take to go 5times around it. solve it nd answer is 9 minutes

Answer 1

Total Area of rectangular field =3584 m²

length of the field is equal to 64 metres

now,
area of rectangle is equal to length X breadth

Thus,

$a = lb \\ \\ b = \frac{a}{l} \\ \\ \\b = \frac{3584}{64} = 56m$

Now ,
breadth of the rectangular field is equal to 56 metre.

we know that the perimeter of rectangle is equal to :-
$2(l + b)$

applying the formula :-

$perimeter = 2(64 + 56) \\ \\ perimeter = 2 \times 120 = 240$

Now,


the boy runs 5 times around the field + the total distance covered by the boy will be equal to perimeter x 5.
So,

distance covered is equal to :-

$240 \times 5 = 1200m$

Now,

Speed of the boy = 8 km/hr
So,
Converting it into m/sec

Speed =
$8 \times \frac{5}{18} m \: per \: sec$

Now,

Time taken = distance/speed

$t = \dfrac{1200 \times 18}{8 \times 5} = 540 \: seconds$

Thus,
Time taken is equal to 540 seconds or 9 minutes.

$1 \: minute = \: 60 \: seconds \\ \\ 540 \: seconds = \frac{540}{60} = 9 \: minutes$