If the ratio of length and breadth of a rectangular park is 5 : 7. If a man cycling along the boundary of the park at a speed of 18 km/h completes one round in 20 minutes, then area of the park is?
Answer & explanation
Correct answer: option 1
Speed of man = 15 km/hr =18 × \(\frac{5}{18}\) = 5 m/sec
Time taken by man to complete round of the park = 20 min = 1200 sec
Perimeter of the park = Length of one round = speed × time
= (5 × 1200) = 6000 m
Length : Breadth = 5 : 7
Perimeter = 2( L + B) = 24R
⇒ 6000 = 24R
⇒ R = 250
∴ sides of park = 7 × 250, 5 × 250 = 1750 m, 1250 m
Area of park = 1250 × 1750 = 21,87,500 m2