Quantitative Aptitude - Arithmetic Ability Questions

Q:

A Cricket team of 23 people all shake hands with each other exactly once. How many hand shakes occur ?

A) 142 B) 175
C) 212 D) 253
 
Answer & Explanation Answer: D) 253

Explanation:

The first person shakes hands with 22 different people, the second person also shakes hands with 22 different people, but one of those handshakes was counted in the 22 for the first person, so the second person actually shakes hands with 21 new people. The third person, 20 people, and so on...
So,
22 + 21 + 20 + 19 + 18 + 17 + 16 + 15 + 14 + 13 + 12 + 11 + 10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1
= n(n+1)/2 = 22 x 23 /2 = 11 x 23 = 253.

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Filed Under: Permutations and Combinations
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4 5988
Q:

Prasanna invested certain amount in three different schemes X, Y and Z with the rate of interest 10% p.a, 12% p.a and 15% p.a respectively. If the total interest accrued in one year was Rs. 3200 and the amount invested in Scheme Z was 150% of the amount invested in Scheme X and 240% of the amount invested in Scheme Y, what was the amount invested in Scheme Y by Prasanna ?

A) Rs.6000 B) Rs.4500
C) Rs.7500 D) Rs.5000
 
Answer & Explanation Answer: D) Rs.5000

Explanation:

Let a, b and c be the amounts invested in schemes X, Y and Z respectively. Then,

As we know:

Simple interest (S.I.) = PTR/100

(a × 10 × 1/100) + (b × 12 × 1/100) + (c × 15 × 1/100) = 3200

= 10a + 12b + 15c = 320000 .........(1)

Now, c = 240% of b = 12b/5 .........(2)

And, c = 150% of a = 3a/2 => a = 2/3 c = (2 × 12)b/(3 × 5) = 8b/5 .......(3)

From (1), (2) and (3), we have

16b + 12b + 36b = 320000 => 64b = 320000 => b = 5000

∴ Sum invested in Scheme Y = Rs.5000.

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Filed Under: Percentage
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9 5987
Q:

5 sin(x)+ 12 cos(x) + r is always greater than or equal to zero. What is the smallest value satisfied by 'r' ?

A) -13 B) 11
C) 13 D) -11
 
Answer & Explanation Answer: C) 13

Explanation:

Given,

 5sinx + 12cosx ≥ -r 

13513sin x + 1213cos x  -rcosx) ≥ -r 

513= cosA => sinA =1213

 

=> 13(sinx cosA + sinA cosx) ≥ -r

 

=> 13(sin(x + A)) ≥ -r

 

we know that , -1 ≤ sin (angle) ≤ 1

 

=> 13sin (x + A) ≥ -13 rmin =13 

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Filed Under: Simplification
Exam Prep: CAT
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8 5982
Q:

The cost price of three varieties of mangoes namely M, N and O is Rs. 20/kg, Rs. 40/kg and Rs. 50/kg respectively. Find the selling price of one kg of mango in which these three varieties of mangoes are mixed in the ratio of 2 : 3 : 5 such that there is a net profit of 20%?

A) Rs. 47 B) Rs. 49.2
C) Rs. 48.5 D) Rs. 50.3
 
Answer & Explanation Answer: B) Rs. 49.2

Explanation:

Total cost of all varieties of mangoes = 20 x 2 + 40 x 3 + 50 x 5 = 40 + 120 + 250 = Rs. 410

Then, cost of 1 kg mangoes = 410/10 = Rs. 41

To get 20% profit,

The rate at which the mangoes should be sell = 120/100 x 41 = Rs. 49.2

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15 5975
Q:

The capacity of a tank is 2400 m3.  A pump can be used both for filling and emptying the tank.  The emptying capacity of the pump is 10 m3/minute higher than its filling capacity. And also, the pump needs 8 minutes less to empty the tank than to fill it. Find the filling capacity of the pump. 

A) 46 cub.m/min B) 44 cub.m/min
C) 48 cub.m/min D) 50 cub.m/min
 
Answer & Explanation Answer: D) 50 cub.m/min

Explanation:

Let filling capacity of the pump be 'F' m3/min

Then, the filling capacity of the pump will be (F + 10) m3/min

From the given data,

2400F - 2400F+10= 8 2400 F+10-FF(F+10) =8 F2 + 10F - 3000 = 0 F = 50 m3/min

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15 5974
Q:

A passenger train is moving at a speed of 120 km/hr. If the length of the train is 101 meters, how long will it take to cross a railway platform 154 meters long ?

A) 6.24 sec B) 6.58 sec
C) 7.325 sec D) 7.65 sec
 
Answer & Explanation Answer: D) 7.65 sec

Explanation:

Here total distance = 154 + 101 = 255 mts
Given speed = 120 kmph = 120x5/18 m/sec
Hence, Time = d/s = 255x18/120x5 = 7.65 sec

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Filed Under: Problems on Trains
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8 5974
Q:

Simple interest on a certain sum of money for 3 years at 8% per annum is half the compound interest on Rs. 4000 for 2 years at 10% per annum. The sum placed on simple interest is

A) Rs.1650 B) Rs.1550
C) Rs.1750 D) Rs.1850
 
Answer & Explanation Answer: C) Rs.1750

Explanation:

C.I. =Rs[4000x(1+10/100)²-4000]

Rs.(4000x11/10x11/10-4000) = Rs.940.

Sum

=Rs. [420 *100 /3 * 8]

= Rs.1750.

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Filed Under: Compound Interest
Exam Prep: Bank Exams
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3 5973
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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2 5965