PS(Geometry)

rintoo22 wrote:The sides of a square region, measured to the
nearest centimeter, are 6 centimeters long. The
least possible value of the actual area of the
square region is
A.36.00 sq cm
B.35.00 sq cm
C.33.75 sq cm
D.30.25 sq cm
E.25.00 sq cm

How to approach such questions ?

The key information here is measured to the nearest centimeter.
So, the sides do not necessarily have length 6.
In fact 5.5 < (length of 1 side) < 6.5

We want the smallest possible area. This will occur when the side lengths are minimized.
The shortest length of each side is 5.5 cm.
So, the smallest possible area = (5.5)(5.5) = [spoiler]30.25 = D[/spoiler]

Cheers,
Brent

As an aside, notice that the question requires us to find (5.5)^2
This is the same as squaring 55 to get 3025 and then moving the decimal over 2 spaces to get 30.25

If anyone is interested, there's a 3-second technique for squaring numbers ending in 5. To learn this technique, watch our free video: https://www.gmatprepnow.com/module/gmat- ... ts?id=1024

Cheers,
Brent