Question

A square water tank has its side equal to 40m, there are 4 semicircular flower beds grassy plots all around it. Find the cost of turfing the plot at Rs 1.25/sq.m

Answer 1

Side of water tank = 40m

Grassy plot is semicircular with radius =`(side)/2=40/2`= 20𝑚 = 𝑟

Area of grassy plot = 4(area od semicircular grassy plot with radius 20m)

`= 4 [1/2`(𝑎𝑟𝑒𝑎 𝑜𝑓 𝑐𝑖𝑟𝑐𝑙𝑒 𝑤𝑖𝑡ℎ 𝑟𝑎𝑑𝑖𝑢𝑠)]

`= 4 ×1/2× pi(20)^2`

= 2 × 20 × 20 × 𝜋 = 800𝜋 𝑚².

Cost of turfing 1m2 = Rs. 1.25

Total cost of turfing the grassy plot around tank

= 800𝜋 × 1.25

= 1000𝜋

= 1000 × 3.14

= Rs. 3140