Question

The inner and outer radii of a circular track are 10 m and 14 m respectively The total cost of levelling the track @ Rs 5/$m^2$ and fencing the inner and outer boundaries of the track @ Rs 20/m is
(use $\pi =3.14$)

• A. Rs $4506.50$
• B. Rs $4726$
• C. Rs $4512.60$
• D. Rs $4521.60$

Answer 1

The correct option is D Rs $4521.60$

Given: $R=14m,r=10m$
Area of track = $3.14\times ({14}^2-{10}^2)=301.44m^2$
Cost of levelling $=$ Rs. $301.44\times 5=$ Rs $1507.20$
Perimeter of track $=2\times 3.14(14+10)m$
$=150.72m$
Cost of fencing $=$ Rs $150.72\times 20$
$=$ Rs $3014.40$
Total cost $=1507.20+3014.40$
$=$ Rs $4521.60$