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Q:

A rectangular grassy plot 110m by 65cm has a gravel path .5cm wide all round it on the inside. Find the cost of gravelling the path at 80 paise per sq.mt

A) 680rs B) 480rs
C) 340rs D) 320rs
 
Answer & Explanation Answer: A) 680rs

Explanation:

area of theplot = 110 * 65 = 7150 sq.m
area of the plot excluding the path = (110-5)* (65-5) = 6300 sq.m
area of the path = 7150 - 6300 =850 sq.m
cost of gravelling the path = 850 x (80/100) = 680 Rs

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11 20707
Q:

If the diagonal of a rectangle is 17cm long and its perimeter is 46 cm. Find the area of the rectangle.

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

Explanation:

let length = x and breadth = y then  

2(x+y) = 46         =>   x+y = 23  

x²+y² = 17² = 289  

now (x+y)² = 23² 

=> x²+y²+2xy= 529 

=> 289+ 2xy = 529

=> xy = 120  

area = xy = 120 sq.cm

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284 78051
Q:

Two concentric circles form a ring. The inner and outer circumference of the ring are 352/7 m and 528/7m respectively.Find the width of the ring.

A) 5 B) 4
C) 3 D) 2
 
Answer & Explanation Answer: B) 4

Explanation:

let the inner and outer radii be r and R meters
then, 2πr = 352/7

 

=> r = (352/7) * (7/22) * (1/2) = 8m
2πR = 528/7

 

=> R= (528/7) * (7/22) * (1/2)= 12m
width of the ring = R-r = 12-8 = 4m

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Q:

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

A) 75% B) 65%
C) 35% D) 25%
 
Answer & Explanation Answer: A) 75%

Explanation:

let original radius = r and  new radius = (50/100) r = r/2

 


original area = πr2 and new area = πr/22

 


decrease in area =  3πr2/4*1πr2 *100 = 75%

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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 = a2 

As given that The side is increased by 25%, then 

New side = 125a/100 = 5a/4 

 

New area = 5a42  

 

Increased area= 25a216-a2 

 

Increase %=9a2/16a2*100  % = 56.25%

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Q:

The altitude drawn to the base of an isosceles triangle is 8cm and the perimeter is 32cm. Find the area of the triangle?

A) 50 B) 60
C) 70 D) 80
 
Answer & Explanation Answer: B) 60

Explanation:

let ABC be the isosceles triangle, the AD be the altitude 

Let AB = AC = x then BC= 32-2x       [because parameter = 2 (side) + Base] 

since in an isoceles triange the altitude bisects the base so 

BD = DC = 16-x 

In a triangle ADC, AC2=AD2+DC2 

x2=82+16-x2 x=10 

BC = 32-2x = 32-20 = 12 cm 

Hence, required area = 12*BC*AD12*12*10 = 60 sq cm

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Q:

In measuring the sides of a rectangle, one side is taken 5% in excess and the other 4% in deficit. Find the error percent in the area, calculate from the those measurements.

A) .7% B) 0.8%
C) 0.9% D) 0.3%
 
Answer & Explanation Answer: B) 0.8%

Explanation:

let x and y be the sides of the rectangle then 

correct area =105100x×96100y 

 

Error% = 504500xy-xy=4500xy %

 

4500xy×1xy×100=45=0.8

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11 18880
Q:

The length of a rectangle is twice its breadth if its length is decreased by 5cm and breadth is increased by 5cm, the area of the rectangle is increased by 75 sq cm. Find the length of the rectangle.

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

Explanation:

let length = 2x and breadth = x then
(2x-5) (x+5) = (2x * x)+75
5x-25 = 75 => x=20
length of the rectangle = 40 cm

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