Quantitative Aptitude - Arithmetic Ability Questions

Q:

There are two containers, the first one contains 1 litre pure water and the second one contains 1 litre pure milk.Now 5 cups of water from the first container is taken out  is mixed well in the second container. Then, 5 cups of this mixture is taken out and is mixed in the first container. Let A denote the proportion of milk in the first container and B denote the proportion of water in the second container then:

A) A B) A=B
C) A>B D) can't be determined
 
Answer & Explanation Answer: B) A=B

Explanation:

Here the ratio of mixtures( i.e milk , water) doesnot matter. But the important point is that whether the total amount ( either pure or mixture ) being transferred is equal or not.Since the total amount ( i.e 5 cups) being transferred from each one to another , hence A =B.

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Filed Under: Ratios and Proportions

18 13885
Q:

A box contains 2 white balls, 3 black balls and 4 red balls. In how many ways can 3 balls be drawn from the box, if at least one black ball is to be included in the draw?

A) 48 B) 64
C) 63 D) 45
 
Answer & Explanation Answer: B) 64

Explanation:

We may have(1 black and 2 non-black) or (2 black and 1 non-black) or (3 black).

 

Required number of ways=3C1*6C2+3C2*6C1+3C3 = (45 + 18 + 1) =64

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5 13867
Q:

The value of x satisfying the following relation:

log12x = log23x-2

A) 1/3 B) -1/3
C) 3 D) None of these
 
Answer & Explanation Answer: D) None of these

Explanation:

But at x=-1/3, log x is not defined.

 

The only admissible value of x is 1.

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Filed Under: Logarithms
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16 13860
Q:

In a simultaneous throw of two dice, what is the probability of getting a doublet ?

A) 1/6 B) 1/3
C) 4/7 D) 4/5
 
Answer & Explanation Answer: A) 1/6

Explanation:

In a simultaneous throw of two dice, n(S) = 6 x 6 = 36

 

Let E = event of getting a doublet = { (1,1), (2,2), (3,3), (4,4), (5,5), (6,6)}

 P(E)=n(E)n(S)=636=16

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Filed Under: Probability

10 13829
Q:

The product of a number and its multiplicative inverse is

A) 1 B) 0
C) -1 D) Infinity
 
Answer & Explanation Answer: A) 1

Explanation:

The mutiplicative inverse of a number is nothing but a reciprocal of a number.

Now, the product of a number and its multiplicative inverse is always equal to 1.

 

For example :

Let the number be 15

Multiplicative inverse of 15 = 1/15

The product of a number and its multiplicative inverse is = 15 x 1/15 = 1.

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Filed Under: Numbers
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21 13807
Q:

A can build a wall in 16 days while B can destroy it in 8 days. A worked for 5 days. Then B joined with A for the next 2 days. Find in how many days could A build the remaining wall ?

A) 12 days B) 14 days
C) 13 days D) 16 days
 
Answer & Explanation Answer: C) 13 days

Explanation:

Now, Total work = LCM(16, 8) = 48

A's one day work = + 48/16 = + 3

B's one day work = - 48/8 = -6

Given A worked for 5 days to build the wall => 5 days work = 5 x 3 = + 15

2days B joined with A in working = 2(3 - 6) = - 6

Remaining Work of building wall = 48 - (15 - 6) = 39

Now this remaining work will be done by A in = 39/3 = 13 days.

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Filed Under: Time and Work
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23 13802
Q:

If you deposit $5000 into an account paying 6% annual interest compounded monthly, how long until there is $8000 in the account?

A) 6.9 B) 7.9
C) 8.9 D) 9.9
 
Answer & Explanation Answer: B) 7.9

Explanation:

 

 

FV=P(1+r/n)^nt

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Filed Under: Compound Interest
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16 13768
Q:

The average of a set of whole numbers is 27.2. when the 20% of the elements are eliminated from the set of numbers then the average become 34. The number of elements in the new set of numbers can be :

A) 27 B) 35
C) 52 D) 63
 
Answer & Explanation Answer: C) 52

Explanation:

only (c) is correct since it is divisible by 4.

 

Let the original number of element  be x then the new no.of elements will be 

 

            4x5 = K                               

 

So K must be divisible by 4

 

Since,      x =  Kx5/4

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Filed Under: Percentage
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12 13759