Bunuel wrote:

gmatbull wrote:

Of an entire rectangular farmland 8m by 10m, Rogers wants to clear a circular space of radius 1m. If he randomly chooses the center of the circular space, what are the chances that he does not extend beyond the edges of the farmland?

A. 0.2

B. 0.5

C. 0.6

D. 0.8

E. 1.0

The center of the circle must be at least one meter from any edge of the farmland. Look at the diagram blow:

Attachment:

Farm.png

If the center is anywhere in the green area, then the circle won't extend beyond the edges.

Therefore, P=favorable/total=(8*6)/(10*8)=0.6.

Answer: C.

Hope it's clear.

if I take the favorable area to be 9*7 then how it is wrong ?

The circle that needs to be drawn can certainly touch the edge, as long as it does not exceed the edge .

So if I leave a distance of 1 meter from each edge , and draw a circle having radius of 1 meter , then the circumference of the circle will certainly coincide with the edges , but not exceed it .

.

According to me 9*7/ 10*8= 63/80=0.78 ->approx - 0.8, Please tell me why this is wrong , what am I missing?

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- Stne