Quantitative Aptitude - Arithmetic Ability Questions

Q:

The average age of students of a class is 15.8 years. The average age of boys in the class is 16.4 years and that of the girls is 15.4 years, The ratio of the number of boys to the number of girls in the class is :

A) 1 : 2 B) 2 : 3
C) 3 : 4 D) 4 : 5
 
Answer & Explanation Answer: B) 2 : 3

Explanation:

 Let the ratio be k : 1. Then,

k * 16.4 + 1 * 15.4 = (k + 1) * 15.8

<=> (16.4 - 15.8) k = (15.8 - 15.4)  <=> k =  0.4/0.6 = 2/3.

Required ratio  = 2/3 : 1 = 2 : 3.

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Filed Under: Average

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Q:

A can finish a work in 18 days and B can do the same work in half the time taken by A. then, working together, what part of the same work they can finish in a day ?

A) Total work B) One-fourth work
C) Half work D) Two-third work
 
Answer & Explanation Answer: C) Half work

Explanation:

A can do the work = 18 days
B can do the work = 18/2 = 9 days
(A + B)'s 1 day work = 1/18 + 1/9 = 1/6
=> In 3 days = 3x1/6 = 1/2 work is completed.

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Filed Under: Time and Work
Exam Prep: AIEEE , Bank Exams , CAT , GATE
Job Role: Bank Clerk , Bank PO

30 24467
Q:

If the arithmetic mean of seventy-five numbers is calculated, it is 35. if each number is increased by 5, then mean of new numbers is :

A) 30 B) 40
C) 50 D) 60
 
Answer & Explanation Answer: B) 40

Explanation:

Let the numbers are x1,x2,.......x75

 

By Hypothesis ,x1+x2+....x7575=35 ......(i)

Mean of new numbers = x1+5+x2+5+.......x75+575

 

x1+x2+......x75+5*7575

 

x1+x2+......x7575+37575=35+5=40 By (i) 

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Q:

Rahul went to purchase a Nokia mobile handset, the shopkeeper told him to pay 20% tax if he asked the bill. Rahul manages to get the discount of 5% on the actual saleprice of the mobile and he paid the shopkeeper Rs. 3325 without tax. Besides he manages to avoid to pay 20% tax on the already  discounted price, what is the amount of discount that he has gotten?

A) 750 B) 375
C) 875 D) 525
 
Answer & Explanation Answer: C) 875

Explanation:

CP = 100, SP (with tax) =120

 

New   SP = 100 - 5 = 95

 

 Effective discount = 120 - 95 = 25 

 

So, at SP of 95 ----> discount = 25

 

and      at SP of 3325 -----> discount = 2595×3325 = 875

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Filed Under: Profit and Loss
Exam Prep: AIEEE , Bank Exams , CAT
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54 24396
Q:

The sum of the number of boys and girls in a school is 150. if the number of boys is x, then the number of girls becomes x% of the total number of students. The number of boys is : 

A) 60 B) 70
C) 80 D) 90
 
Answer & Explanation Answer: A) 60

Explanation:

We have : x + (x% of 150 )= 150 

=> x+(x/100)*150] = 150

=> 52x = 150  

=> x = (150*2)/5 = 60

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Filed Under: Percentage

43 24384
Q:

∆PQR is right angled at Q. If m∠P = 60 deg, then find the value of (secR + 1/2).

 

A) (2√2+√3)/2   B) (√3+4)/2√3
C) √3+2   D) 5/6
 
Answer & Explanation Answer: B) (√3+4)/2√3

Explanation:
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Filed Under: Volume and Surface Area
Exam Prep: Bank Exams

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Q:

The present worth of Rs.169 due in 2 years at 4% per annum compound interest is

A) Rs.156.25 B) Rs.150
C) Rs.140 D) Rs125.25
 
Answer & Explanation Answer: A) Rs.156.25

Explanation:

 

Present Worth

 

=P1+R1002

 

=1691+41002

 

= Rs.156.25

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

30 24353
Q:

A fort had provision of food for 150 men for 45 days. After 10 days, 25 men left the fort. The number of days for which the remaining food will last, is:

A) 29/5 B) 37/4
C) 42 D) 54
 
Answer & Explanation Answer: C) 42

Explanation:

After 10 days : 150 men had food for 35 days.

 

 

 

Suppose 125 men had food for x days.

 

 

 

Now, Less men, More days (Indirect Proportion)

 

 

 

 125 : 150 :: 35 : x    =>    125 x x = 150 x 35

 

 

 

 =>

 

 

 

=> x = 42.

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