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Q:

A hall is 15 m long and 12 m broad. If the sum of the areas of the floor and the ceiling is equal to the sum of the areas of four walls, the volume of the hall is:

A) 720	B) 900
C) 1200	D) 1800

Answer & Explanation Answer: C) 1200

Explanation:

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Q:

A tank is 25 m long, 12 m wide and 6 m deep. The cost of plastering its walls and bottom at 75 paise per sq. m, is:

A) Rs. 456	B) Rs. 458
C) Rs. 558	D) Rs. 568

Answer & Explanation Answer: C) Rs. 558

Explanation:

Area to be plastered= [2(l + b) x h] + (l x b)

= [2(25 + 12) x 6] + (25 x 12)

= (444 + 300)

= 744

Cost of plastering = Rs. 744 x (75/100)= Rs. 558

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Q:

The difference between the length and breadth of a rectangle is 23 m. If its perimeter is 206 m, then its area is:

A) 1520 sq.m	B) 2420 sq.m
C) 2480 sq.m	D) 2520 sq.m

Answer & Explanation Answer: D) 2520 sq.m

Explanation:

We have: (l - b) = 23 and 2(l + b) = 206 or (l + b) = 103.

Solving the two equations, we get: l = 63 and b = 40.

Area = (l x b) = (63 x 40) sq.m

= 2520 sq.m

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Q:

The diagonal of a rectangle is sqrt(41) cm. and its area is 20 sq. cm. The perimeter of the rectangle must be:

A) 9 cm	B) 18 cm
C) 20 cm	D) 41 cm

Answer & Explanation Answer: B) 18 cm

Explanation:

$l^{2} + b^{2}$ = ${(d i a g o n a l)}^{2}$ =40

Also, lb=20

${(l + b)}^{2} = l^{2} + b^{2} + 2 l b$ = 41 + 40 =81

(l + b) = 9.

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

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Q:

A towel, when bleached, was found to have lost 20% of its length and 10% of its breadth. The percentage of decrease in area is:

A) 10%	B) 10.08%
C) 20%	D) 28%

Answer & Explanation Answer: D) 28%

Explanation:

Let original length = x and original breadth = y.

Decrease in area = xy -[(80/100x) * (90/100y)]

=[(xy-(18/25)xy)]

=(7/25)xy

Decrease % =[(7/25)xy * (1/xy) * 100] =28%

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Q:

The diagonal of the floor of a rectangular closet is $7 \frac{1}{2}$ feet. The shorter side of the closet is $4 \frac{1}{2}$ feet. What is the area of the closet in square feet?

A) 5 .5	B) 13.5
C) 27	D) 37

Answer & Explanation Answer: C) 27

Explanation:

Other side= $\sqrt{[{(\frac{15}{2})}^{2} - (\frac{9^{2}}{2})]} f t$ = $\sqrt{\frac{225}{4} - \frac{81}{4}} f t$ = $\sqrt{\frac{144}{4}}$ = 6ft

Area of closet =(6 x 4.5)sq.ft = 27 sq.ft

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Q:

The ratio between the perimeter and the breadth of a rectangle is 5 : 1. If the area of the rectangle is 216 sq. cm, what is the length of the rectangle?

A) 16cm	B) 18cm
C) 24cm	D) .Data inadequate

Answer & Explanation Answer: B) 18cm

Explanation:

2(l+b)/b = 5/1

=> 2l + 2b = 5b

=> 3b = 2l

=> b =(2/3) x l

Then, Area = 216 sq.cm

l x b = 216

=> l x [(2/3)x l] =216

=> l x l = 324

=> l = 18 cm.

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Q:

An error 2% in excess is made while measuring the side of a square. The percentage of error in the calculated area of the square is:

A) 2%	B) 2.02%
C) 4%	D) .4.04%

Answer & Explanation Answer: D) .4.04%

Explanation:

100 cm is read as 102 cm.

A1 = (100 x 100) and A2 =(102 x 102)

(A2 - A1) = [(102 x 102)-(100 x 100) ]= 404

Percentage error =[404/(100 x 100 )] x 100%= 4.04%

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