Q:

If each side of a square is increased by 25%, find the percentage change in its area?

A) 65.25 B) 56.25
C) 65 D) 56
 
Answer & Explanation Answer: B) 56.25

Explanation:

let each side of the square be a , then area = a x a

New side = 125a / 100 = 5a / 4

New area =(5a x 5a) / (4 x 4) = (25a²/16) 

increased area== (25a²/16) - a²

Increase %= [(9a²/16 ) x (1/a² ) x 100]% = 56.25%

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Q:

If the radius of a circle is decreased by 50%, find the percentage decrease in its area.

A) 55% B) 65%
C) 75% D) 85%
 
Answer & Explanation Answer: C) 75%

Explanation:

Let original radius = R.

New radius = 

Original area =  and new area = 

Decrease in area =  = 75%

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Q:

A man walked diagonally across a square lot. Approximately, what was the percent saved by not walking along the edges?

A) 30 B) 40
C) 50 D) 60
 
Answer & Explanation Answer: A) 30

Explanation:

Let the side of the square(ABCD) be x meters.

Then, AB + BC = 2x metres.

AC =  = (1.41x) m.

Saving on 2x metres = (0.59x) m.

Saving % = = 30% (approx)

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Q:

The diagonal of a rectangle is  cm and its area is 20 sq. cm. The perimeter of the rectangle must be:

A) 18 B) 28
C) 38 D) 48
 
Answer & Explanation Answer: A) 18

Explanation:

 (or)   {\color{Black} l^{2}+b^{2}=41}

Also, 

{\color{Black} (l+b)^{2}=l^{2}+b^{2}+2lb}

          = 41 + 40 = 81

(l + b) = 9.

Perimeter = 2(l + b) = 18 cm.

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103 6689
Q:

One side of a rectangular field is 15m and one of its diagonal is 17m. Find the area of field?

A) 110 B) 120
C) 130 D) 140
 
Answer & Explanation Answer: B) 120

Explanation:

Other side = [(17 x 17) - (15 x 15)] = (289 - 225) = 8m
Area = 15 x 8 =120 sq. m

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