question_answer

A square water tank has its sides equal to 40 m. There are four semicircular grassy plots all round it. Find the cost of turfing the plots at \[Rs.\text{ }1.25\]per sq. m.           

A)  Rs.2671        

B)  Rs.4401                     

C)  Rs.2512        

D)         Rs.3140

Correct Answer: D

Solution :

\[AB=40\text{ }m\]           and radius of semicircular plot  \[=\frac{40}{2}=20\,m\] Area of 4 circular plots  \[=4\times \] (Area of semi circle) \[=4\times \frac{1}{2}\times \pi \times {{20}^{2}}\] \[=2\times 3.14\times 400=2512\,{{m}^{2}}\] Cost of turfing the plots at the rate Rs.1.25 per sq. \[m=2512\times 1.25=Rs.3140\]