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Q:

Compute the sum of 4 digit numbers which can be formed with the four digits 1,3,5,7, if each digit is used only once in each arrangement.

A) 105555	B) 106665
C) 106656	D) 108333

Answer & Explanation Answer: C) 106656

Explanation:

The number of arrangements of 4 different digits taken 4 at a time is given by $4 P_{4}$ = 4! = 24.All the four digits will occur equal number of times at each of the position,namely ones,tens,hundreds,thousands.

Thus,each digit will occur 24/4 = 6 times in each of the position.The sum of digits in one's position will be 6 x (1+3+5+7) = 96.Similar is the case in ten's,hundred's and thousand's places.

Therefore,the sum will be 96 + 96 x 10 + 96 x 100 + 96 x 100 = 106656

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Q:

A room is half as long again as it is broad. The cost of carpeting the at Rs. 5 per sq.m is Rs. 270 and the cost of papering the four walls at Rs. 10 per sq.m is Rs. 1720. If a door and 2 windows occupy 8 sq. m, find the dimensions of the room.

A) b=6; l=18; H=6	B) b=5; l=6; H=18
C) l=6; b=18; H=15	D) l=5; b=18; H=18

Answer & Explanation Answer: A) b=6; l=18; H=6

Explanation:

Let breadth = x metres, length = 3x metres, height = H metres.

Area of the floor=(Total cost of carpeting)/(Rate) = (270/5) sq.m = 54 sq.m

$x \times \frac{3 x}{2} = 54 \Rightarrow x^{2} = 54 \times 2 \Rightarrow x = 6$

So, breadth = 6 m and length = $\frac{3 (6)}{2}$ = 9 m.

Now, papered area = (1720/10) = 172 sq.m

Area of 1 door and 2 windows = 8 sq.m

Total area of 4 walls = (172 + 8) sq.m = 180 sq.m

$2 \times (9 + 6) H = 180 \Rightarrow H = 6$

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Filed Under: Area
Exam Prep: Bank Exams
Job Role: Bank PO

Q:

If the length of a certain rectangle is decreased by 4 cm and the width is increased by 3 cm, a square with the same area as the original rectangle would result. Find the perimeter of the original rectangle.

A) 20	B) 30
C) 40	D) 50

Answer & Explanation Answer: D) 50

Explanation:

Let x and y be the length and breadth of the rectangle respectively.
Then, x - 4 = y + 3 or x - y = 7 ----(i)
Area of the rectangle =xy; Area of the square = (x - 4) (y + 3)
(x - 4) (y + 3) =xy <=> 3x - 4y = 12 ----(ii)
Solving (i) and (ii), we get x = 16 and y = 9.
Perimeter of the rectangle = 2 (x + y) = [2 (16 + 9)] cm = 50 cm.

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Filed Under: Area
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Q:

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

A) 56.25%	B) 36.25%
C) 16.25%	D) 12.25%

Answer & Explanation Answer: A) 56.25%

Explanation:

Let each side of the square be a. Then, area = . $a^{2}$
New side = $\frac{125 a}{100} = \frac{5 a}{4}$ . New area = ${(\frac{5 a}{4})}^{2}$ = $(\frac{25 a^{2}}{16})$

Increase in area = $\frac{25 a^{2}}{16} - a^{2} = \frac{9 a^{2}}{16}$
Increase% = $[\frac{9 a^{2}}{16} * \frac{1}{a^{2}} * 100]$ % = 56.25%.

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Q:

In how many different ways can 3 students be associated with 4 chartered accountants,assuming that each chartered accountant can take at most one student?

A) 12	B) 36
C) 24	D) 16

Answer & Explanation Answer: C) 24

Explanation:

Number of permutations = $4 P_{3}$ = 24

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Q:

First,second and third prizes are to be awarded at an engineering fair in which 13 exhibits have been entered.In how many different ways can the prizes be awarded?

A) 1736	B) 1716
C) 1216	D) 1346

Answer & Explanation Answer: B) 1716

Explanation:

$13 P_{3}$ = 13!/10! = 1716

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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.458	B) rs,558
C) rs.658	D) rs.758

Answer & Explanation Answer: B) 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 sq.m

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

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Filed Under: Area
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Q:

A rectangular field is to be fenced on three sides leaving a side of 20 feet uncovered. If the area of the field is 680 sq. feet, how many feet of fencing will be required?

A) 22	B) 44
C) 66	D) 88

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