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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:   C) 75%

Explanation:

Let original radius = R.

New radius = 

Original area =  and new area = 

Decrease in area =  = 75%

Q:

If a 36 cm thread is used to wrap a book, lengthwise twice and breadth wise once, what is the size of the book ?

A) 288 sq.cm B) 188 sq.cm
C) 144 sq.cm D) 244 sq.cm
 
Answer & Explanation Answer: A) 288 sq.cm

Explanation:

Length of the thread is 36 cms.
length wise twice breath wise once then totally thrice.
so 36/3 = 12.
so length is 12 x 2 = 24 cms
breath is 12 cms
Area of the book = length x breath = 24 x 12 = 288 sq.cm

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2 36
Q:

If 4 circles of equal radius are drawn with vertices of a square as the centre , the side of the square being 7 cm, find the area of the circles outside the square ?

A) 119.21 sq cm B) 115.395 sq cm
C) 104.214 sq cm D) 111.241 sq cm
 
Answer & Explanation Answer: B) 115.395 sq cm

Explanation:

Because each vertice of the square is the center of a circle
(1/4) part of the total area of each circle inside of the square.
(3/4) part of the total area of each circle outside of the square.
Thus total area outside the square is = 115.3955 sq cm.

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2 42
Q:

What is the least number of squares tiles required to pave the floor of a room 15 m 17 cm long and 9 m 2 cm broad ?

A) 844 B) 814
C) 840 D) 820
 
Answer & Explanation Answer: B) 814

Explanation:

Length of largest tile = H.C.F. of 1517 cm and 902 cm = 41 cm.
Area of each tile = (41 x 41) sq.cm

Required number of tiles =1517 x 902/(41 x 41) = 814.

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4 141
Q:

A rectangular grassy plot 120 m. by 60 m has a gravel path 1.5 m wide all round it on the inside. Find the cost of gravelling the path at 65 paise per sq. metre ?

A) Rs. 345.15 B) Rs. 245.1
C) Rs. 234.18 D) Rs. 456.65
 
Answer & Explanation Answer: A) Rs. 345.15

Explanation:

area of the plot = 120m x 60m = 7200 sq.m
area of plot excluding gravel = 117m x 57m = 6669 sq.m
area of gravel = 7200 sq.m - 6669 sq.m = 531 sq.m
cost of building it = 531 sq.m x 65 ps
= 34515 ps
In Rs. = 34515/100 = Rs. 345.15.

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Filed Under: Area - Quantitative Aptitude - Arithmetic Ability
Exam Prep: Bank Exams , CAT
Job Role: Bank PO

4 48
Q:

The area of a square is 1024 sq.cm. What is the ratio of the length to the breadth of a rectangle whose length is twice the side of the square and breadth is 12 cm less than the side of this square ?

A) 14:9 B) 13:12
C) 16:5 D) 17:13
 
Answer & Explanation Answer: C) 16:5

Explanation:

Area of a square SxS = 1024 => S = 32 cm
Length of the rectangle = 32x2 cm = 64 cm
Breadth of the rectangle = 32 - 12 = 20 cm
Required ratio = 64 : 20 = 16 : 5

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