Quantitative Aptitude - Arithmetic Ability Questions

Q:

A perfect cube is an integer whose cube root is an integer. For example, 27, 64 and 125 are perfect cubes. If p and q are perfect cubes, which of the following will not necessarily be a perfect cube?

A) 8p B) pq
C) pq+27 D) -p
 
Answer & Explanation Answer: C) pq+27

Explanation:

A perfect cube will have prime factors that are in groups of 3; for example 125 has the prime factors 5 x 5 x 5 , and 64 x 125 will also be a cube because its factors will be 4 x 4 x 4 x 5 x 5 x 5

Consider the answer choices in turn.

8 is the cube of 2, and p is a cube, and so the product will also be a cube.

pq will also be a cube as shown above.

pq is a cube and so is 27, but their sum need not be a cube. Consider the case where p =1 and q = 8, the sum of pq and 27 will be 35 which has factors 5 x 7 and is not a cube.

-p will be a cube.

Since the difference between p and q is raised to the power of 6, this expression will be a cube (with cube root = difference squared).

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Filed Under: Numbers

7 11754
Q:

The angle between the minute hand and the hour hand of a clock when the time is 4.20, is:

A) 0 B) 10
C) 30 D) 60
 
Answer & Explanation Answer: B) 10

Explanation:

Angle traced by hour hand in 133hrs = 36012×13301300 

Angle traced by min. hand in 20 min = 36060×200 =1200 

Required angle = (130 - 120)º = 10º

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

18 11722
Q:

In what time will Rs. 1860 amount to Rs. 2641.20 at simple interest 12% per annum?

A) 2.9 years B) 3.5 years
C) 4.2 years D) 4.7 years
 
Answer & Explanation Answer: B) 3.5 years

Explanation:

Given that Rs. 1860 will become Rs. 2641.20 at 12%

 

=> Simple Interest = 2641.20 - 1860 = Rs. 781.20

 

We know I = PTR/100

 

=> 781.20 x 100 = 1860 x T x 12

 

=> T = 78120/1860x12

 

=> T = 78120/22320

 

=> T = 3.5 years.

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Filed Under: Simple Interest
Exam Prep: GATE , CAT , Bank Exams , AIEEE
Job Role: Bank PO , Bank Clerk

30 11716
Q:

Karthik read 613 th of a book in 1st week and 59 th of the remaining book in 2nd week. If there were 100 pages unread after 2nd week, how many pages were there in the book ?

A) 404 B) 415
C) 418 D) 420
 
Answer & Explanation Answer: C) 418

Explanation:

Let the total book be 1

Then, in the 1st week 613th of book is read

i.e remaining pages =  1-613=713


in 2nd week he read 59th of it

i.e 59×713=35117
Remaining pages after 2nd week = 713-35117=28117

But given remaining pages after 2nd week = 100

 

28x117=100

--> x = 418 

 The total pages in the book are 418

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Filed Under: Decimal Fractions
Exam Prep: GATE , CAT , Bank Exams
Job Role: Bank PO , Bank Clerk

17 11706
Q:

The height of the wall is 6 times its width and lenght of the wall is 7 times its height .if the volume of the wall be 16128 cu.m.its width is

A) 4m B) 5m
C) 6m D) 7m
 
Answer & Explanation Answer: A) 4m

Explanation:

Let width = x

Then, height = 6x and length = 42x 

42x * 6x * x = 16128

x = 4

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Filed Under: Volume and Surface Area
Exam Prep: Bank Exams
Job Role: Bank PO

12 11701
Q:

Two passenger trains start at the same hour in the day from two different stations and move towards each other at the rate of 16 kmph and 21 kmph respectively. When they meet, it is found that one train has traveled 60 km more than the other one. The distance between the two stations is ?

A) 387 kms B) 242 kms
C) 145 kms D) 444 kms
 
Answer & Explanation Answer: D) 444 kms

Explanation:

1h ----- 5 kms
? ------ 60 kms

Time = 12 hrs

Relative Speed = 16 + 21 = 37 kmph

T = 12 hrs

D = S x T = 37 x 12 = 444 kms.

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Filed Under: Problems on Trains
Exam Prep: AIEEE , Bank Exams , CAT
Job Role: Bank Clerk , Bank PO

11 11696
Q:

Find the one which does not belong to that group ?

A) 343 B) 2197
C) 1331 D) 121
 
Answer & Explanation Answer: D) 121

Explanation:

343 = 73,  1331 = 113 , 2197 = 133, 121 = 112

 

343, 1331, 2197 are perfect cubes, but not 121.

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Filed Under: Odd Man Out
Exam Prep: GATE , CAT , Bank Exams , AIEEE
Job Role: Bank PO , Bank Clerk

12 11671
Q:

If a - b = 3,  a2+b2=29, find the value of ab.

A) 10 B) 12
C) 15 D) 18
 
Answer & Explanation Answer: A) 10

Explanation:

2ab=a2+b2-a2-b2

 

29-9=20

=>ab=10

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Filed Under: Simplification

8 11669