SSC CHSL 6 Dec 2015 Shift 2 Paper

Question : 142 of 200

Marks: +1, -0

The outer circumference of a circular race track is 528 metre. The track is every where 14 metre wide.
Cost of levelling the track at the rate of ₹10 per sq. metre is:

₹77660
₹76760
₹66760
₹67760

Validate

Solution:

Let outer radius = m and inner radius =

r=(R-14)

m
Outer circumference =

2πR = 528

⇒

2 ×22/ 7 ×R = 528

⇒

R=528×7/44=84

m
Thus, inner radius =

84-14=70

m
⇒ Area of track =

π(R^2 − r^2 )

22/7 (R +r)(R − r)

22/7 (84 +70)(84 − 70)

22/7×154 × 14 = 6776 m^2

∴ Total cost of levelling = 6776 × 10 = Rs. 67, 760

Go to Question:

Prev Question

Next Question