Quantitative Aptitude - Arithmetic Ability Questions

Q:

A mother can do a certain job in x hours. Her daughter takes twice as long to do the job. Working together, they can do the job in 6 hours. How many hours does the mother take to do the job ?

A) 3 B) 6
C) 9 D) 12
 
Answer & Explanation Answer: C) 9

Explanation:

The mother completes the job in x hours.
So, the daughter will take 2x hours to complete the same job.

 

In an hour, the mother will complete 1/x of the total job.
In an hour, the daughter will complete 1/2x of the total job.

 

So, if the mother and daughter work together, in an hour they will complete 1/x + 1/2x of the job.
i.e., in an hour they will complete 3/2x of the job.

 

The question states that they complete the entire task in 6 hours if they work together.
i.e., they complete 1/6 th of the task in an hour.

 

Equating the two information, we get 3/2x = 1/6
By solving for x, we get 2x = 18 or x = 9.

 

The mother takes 9 hours to complete the job.

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Filed Under: Time and Work
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8 5779
Q:

Find the sum of the all the numbers formed by the digits 2,4,6 and 8 without repetition. Number may be of any of the form like 2,24,684,4862 ?

A) 133345 B) 147320
C) 13320 D) 145874
 
Answer & Explanation Answer: B) 147320

Explanation:

Sum of 4 digit numbers = (2+4+6+8) x P33 x (1111) = 20 x 6 x 1111 = 133320 


Sum of 3 digit numbers = (2+4+6+8) x P23 x (111) = 20 x 6 x 111 = 13320 


Sum of 2 digit numbers = (2+4+6+8) x P13 x (11) = 20 x 3 x 11 = 660 


Sum of 1 digit numbers = (2+4+6+8) x P03 x (1) = 20 x 1 x 1 = 20 

 

Adding All , Sum = 147320

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Filed Under: Permutations and Combinations
Exam Prep: CAT , Bank Exams
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2 5768
Q:

What is the SI on Rs.7500/- at the rate of 10% per annum for 5 years?

A) 3750 B) 2750
C) 1750 D) 750
 
Answer & Explanation Answer: A) 3750

Explanation:

S.I=PNR/100

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Filed Under: Simple Interest
Exam Prep: Bank Exams
Job Role: Bank PO

4 5756
Q:

The age of Manisha and Sudeshna are in the ratio of 5 : 6 respectively. After 8 years the ratio  of their ages will be 7 : 8. What is the difference of their ages ?

A) 6 B) 4
C) 8 D) 10
 
Answer & Explanation Answer: B) 4

Explanation:

Let the age of Manisha and Sudeshna is 5x and 6x years respectively.

According to the given data,

5x+8/6x+8 = 7/8

42x + 56 = 40x + 64

x = 4

Required Difference of their ages = (6 × 4)  –  (5 × 4)

= 4 years.

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Filed Under: Problems on Ages
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8 5753
Q:

The ratio between the length and the breadth of a rectangular park is 3 : 2. If a man cycling along the boundary of the park at the speed of 12 km/hr completes one round in 8 minutes, then the area of the park (in sq. m) is:

A) 15360 B) 153600
C) .30720 D) 307200
 
Answer & Explanation Answer: B) 153600

Explanation:

Perimeter = Distance covered in 8 min. = (12000/60) * 8 = 1600m 

Let length = 3x metres and breadth = 2x metres.  

Then, 2(3x + 2x) = 1600 or x = 160.  

Length = 480 m and Breadth = 320 m.

Area = (480 x 320) = 153600 

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0 5752
Q:

The Simple Interest & True Discount on a certain sum of money for a given time & at a given rate are Rs 85 & Rs.80.The sum is:

A) Rs.1350 B) Rs.1360
C) Rs.1316 D) Rs.1200
 
Answer & Explanation Answer: B) Rs.1360

Explanation:

Sum = [(S.I x T.D)/(S.I-T.D)] = (85 x 80)/(85-80) = Rs.1360

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Filed Under: True Discount

1 5748
Q:

A certain amount earns simple interest of Rs. 2260 after 3 years. Had the interest been 1 % more how much more interest would it have earned ?

A) Rs. 175 B) Rs. 220.75
C) Rs. 126 D) Can't be determined
 
Answer & Explanation Answer: D) Can't be determined

Explanation:

Here given Interest earned = Rs. 2260

Time = 3 years

Rate of interest = ?

Principal Amount = ?

So, it can't be determined.

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Filed Under: Simple Interest
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18 5744
Q:

The difference between the length and breadth of a rectangle is 23 m. If its perimeter is 206 m, then its area is:

A) 1520 sq.m B) 2420 sq.m
C) 2480 sq.m D) 2520 sq.m
 
Answer & Explanation Answer: D) 2520 sq.m

Explanation:

We have: (l - b) = 23 and 2(l + b) = 206 or (l + b) = 103. 

Solving the two equations, we get: l = 63 and b = 40. 

Area = (l x b) = (63 x 40) sq.m

= 2520 sq.m

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1 5743