Quantitative Aptitude - Arithmetic Ability Questions

Q:

Hari Ram’s present age is three times his son’s present age and two fifth of his father’s present age. The average of the present age of all of them is 46 years. What is the difference between Hari Ram’s son’s present age and Hari Ram’s father’s present age? 

A) 44 yrs B) 56 yrs
C) 67 yrs D) 78 yrs
 
Answer & Explanation Answer: D) 78 yrs

Explanation:

Let Hari Ram's present age = x

Then, his son's age = x/3

Father's age = 5x/2

x + x3 + 52x3 = 46=> x = 36 yrs

Now the required difference = 52x36 - 363 = 78 yrs

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Filed Under: Problems on Ages
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11 8950
Q:

From a tank of petrol, which contains 200 litres of petrol, the seller replaces each time with kerosene when he sells 40 litres of petrol(or its mixture). Everytime he sells out only 40 litres of petrol(pure or impure). After replacing the petrol with kerosen 4th time, the total amount of kerosene in the mixture is 

A) 81.92L B) 96L
C) 118.08L D) None of these
 
Answer & Explanation Answer: C) 118.08L

Explanation:

The amount of petrol left after 4 operations  

200 × 1-402004  

200 × 454  

200 × 256625  

= 81.92 litres

 

Hence the amount of kerosene = 200 - 81.92 = 118. 08 litres

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Filed Under: Alligation or Mixture
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9 8947
Q:

The number 0.127 is how much greater than 1/8 ?

A) 1/100 B) 1/1500
C) 1/2 D) 1/500
 
Answer & Explanation Answer: D) 1/500

Explanation:

0.127 expressed as a fraction = 127/1000

1/8 can also be expressed as (1 x 125) / (8 x 125) = 125/1000

The difference is 2/1000, which is 1/500

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Filed Under: Decimal Fractions
Exam Prep: GRE

8 8944
Q:

A box contains 4 different black balls, 3 different red balls and 5 different blue balls. In how many ways can the balls be selected if every selection must have at least 1 black ball and one red ball ?

A) 24 - 1  

B) 2425-1   

C) (24-1)(23-1)25   

D) None 

A) A B) B
C) C D) D
 
Answer & Explanation Answer: C) C

Explanation:

It is explicitly given that all the 4 black balls are different, all the 3 red balls are different and all the 5 blue balls are different. Hence this is a case where all are distinct objects.

 

Initially let's find out the number of ways in which we can select the black balls. Note that at least 1 black ball must be included in each selection.

 

Hence, we can select 1 black ball from 4 black balls
or 2 black balls from 4 black balls.
or 3 black balls from 4 black balls.
or 4 black balls from 4 black balls.

 

Hence, number of ways in which we can select the black balls

 

= 4C1 + 4C2 + 4C3 + 4C4
= 24-1 ........(A)

 

Now let's find out the number of ways in which we can select the red balls. Note that at least 1 red ball must be included in each selection.

 

Hence, we can select 1 red ball from 3 red balls
or 2 red balls from 3 red balls
or 3 red balls from 3 red balls

 

Hence, number of ways in which we can select the red balls
= 3C1 + 3C2 + 3C3
=23-1........(B)

 

Hence, we can select 0 blue ball from 5 blue balls (i.e, do not select any blue ball. In this case, only black and red balls will be there)
or 1 blue ball from 5 blue balls
or 2 blue balls from 5 blue balls
or 3 blue balls from 5 blue balls
or 4 blue balls from 5 blue balls
or 5 blue balls from 5 blue balls.

 

Hence, number of ways in which we can select the blue balls
= 5C0 + 5C1 + 5C2 + … + 5C5
= 25..............(C)

 

From (A), (B) and (C), required number of ways
=  2524-123-1

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Filed Under: Permutations and Combinations
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3 8921
Q:

There is an empty reservoir whose capacity is 30 litres. There is an inlet pipe which fills at 5 L/min and there is an outlet pipe which empties at 4 L/min. Both the pipes function alternately for 1 minute. Assuming that the inlet pipe is the first one to function, how much time will it take for the reservoir to be filled up to its capacity?

A) 49.5 min B) 50 min
C) 51 min D) 52 min
 
Answer & Explanation Answer: C) 51 min

Explanation:

The work to be done = Capacity of reservoir  = 30 litres.

 1st Minute ---> inlet pipe opened ---> 5 lit filled

 2nd minute ---> inlet pipe closed; outlet pipe opened ---> 4 lit emptied

 

In 2 minutes (5 litres - 4 litres = 1lit) is filled into the reservoir.

It takes 2 minutes to fill 1lit ---> it takes 50 minutes to fill 25 litres into the reservoir.  

 

In the 51st minute inlet pipe is opened and the reservoir is filled.

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Filed Under: Pipes and Cistern
Exam Prep: CAT
Job Role: Bank PO

24 8912
Q:

Pipe K fills a tank in 30 minutes. Pipe L can fill the same tank 5 times as fast as pipe K. If both the pipes were kept open when the tank is empty, how much time will it take for the tank to overflow ?

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

Explanation:

Let the total capacity of tank be 90 liters.
Capacity of tank filled in 1 minute by K = 3 liters.
Capacity of tank filled in 1 minute by L = 15 liters.
Therefore, capacity of the tank filled by both K and L in 1 minute = 18 liters.
Hence, time taken by both the pipes to overflow the tank = 90/18 = 5 minutes.

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11 8912
Q:

The ratio of Karthik’s and Kalyan’s ages is 4: 5. If the difference between the present age of Kalyan and the age of Karthik 5 years hence is 3 years, then what is the total of present ages of Karthik and Kalyan?

A) 56 years B) 62 years
C) 69 years D) 72 years
 
Answer & Explanation Answer: D) 72 years

Explanation:

Let us consider Karthik as K1 and Kalyan as K2.


Given k18+k1 and K2 - (K1 + 5) = 3 

K2 - K1 = 8

K2 = 8 + K1

Now, 

k18+k1= 45

=> K1 = 32 years

Therefore K2 = 40 years.

K1 + K2 = 72 years.

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Filed Under: Problems on Ages
Exam Prep: CAT
Job Role: Bank PO

7 8887
Q:

There are 44 students in a hostel, due to the administration,  15 new students has joined. The expense of the mess increase by Rs. 33 per day. While the average expenditure per head diminished by Rs. 3, what was the original expenditure of the mess ?

A) Rs. 404 B) Rs. 514
C) Rs. 340 D) Rs. 616
 
Answer & Explanation Answer: D) Rs. 616

Explanation:

Let the average expenditure per head be Rs. p
Now, the expenditure of the mess for old students is Rs. 44p
After joining of 15 more students, the average expenditure per head is decreased by Rs. 3 => p-3
Here, given the expenditure of the mess for (44+15 = 59) students is increased by Rs. 33
Therefore, 59(p-3) = 44p + 33
59p - 177 = 44p + 33
15p = 210
=> p = 14
Thus, the expenditure of the mess for old students is Rs. 44p = 44 x 14 = Rs. 616.

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Filed Under: Average
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11 8876