Quantitative Aptitude - Arithmetic Ability Questions

Q:

One of the roots of the equation x2 - 6x + k = 0 is x = 2. The other root is

 

A) x = -1 B) x = 4
C) x = -4 D) x = 1
 
Answer & Explanation Answer: B) x = 4

Explanation:
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Filed Under: Area
Exam Prep: Bank Exams

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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:

If 8 men can reap 80 hectares in 24 days , then how many hectares can 36 men reap in 30 days?

A) 350 B) 400
C) 425 D) 450
 
Answer & Explanation Answer: D) 450

Explanation:

Let the required no of hectares be x. Then 

More men, More hectares      (Direct proportion)

More days, More hectares      (Direct proportion)

 Men8 : 36Days24:30 80 :x

=> ( 8 * 24 * x) = (36 * 30 * 80)

=>  x= 450

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Filed Under: Chain Rule

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Q:

Based on the analogy given, find the missing number from the given options.

 

11 : 13 :: 17 : ___

 

A) 29 B) 21
C) 19 D) 23
 
Answer & Explanation Answer: D) 23

Explanation:
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Filed Under: Ratios and Proportions
Exam Prep: Bank Exams

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Q:

The ages of Krish and Vaibhav are in the proportion of 3 : 5. After 9 years, the proportion of their ages will be 3 : 4. Then the current age of Vaibhav is:

A) 10 B) 13
C) 15 D) 18
 
Answer & Explanation Answer: C) 15

Explanation:

Krish’s age = 3A and Vaibhav’s age = 5A


(3A+9)/(5A+9) = 3/4


=> 4 (3A + 9) = 3 (5A + 9)


=> A = 3


Therefore, Vaibhav’s age = 15 years.

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Filed Under: Problems on Ages

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Q:

The H.C.F and L.C.M of two numbers are  84 and 21 respectively.  If the ratio of the two numbers is 1 : 4 , then the larger of the two numbers is 

A) 12 B) 48
C) 84 D) 108
 
Answer & Explanation Answer: C) 84

Explanation:

Let the numbers be x and 4x. Then,  x×4x=84×21  x2=84×214 x=21 

Hence Larger Number = 4x = 84

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Filed Under: HCF and LCM

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Q:

In a college, the ratio of the number of boys to girls is 8 : 5. If there are 160 girls, the total number of students in the college is

A) 100 B) 250
C) 260 D) 416
 
Answer & Explanation Answer: D) 416

Explanation:

Let the number of boys and girls be 8x and 5x.
Total number of students = 13x = 13 * 32 = 416.

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Filed Under: Ratios and Proportions

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Q:

A man invests Rs.5000 for 3 years at 5% p.a. compound interest reckoned yearly. Income tax at the rate of 20% on the interest earned is deducted at the end of each year. Find the amount at the end of the third year

A) Rs.5624.32 B) Rs.5423
C) Rs.5634 D) Rs.5976
 
Answer & Explanation Answer: A) Rs.5624.32

Explanation:

 

 

 

5% is the rate of interest. 20% of the interest amount is paid as tax.

 

i.e  80% of the interest amount stays back.

 

 if we compute the rate of interest as 80% of 5% = 4% p.a., we will get the same value.

  

The interest accrued for 3 years in compound interest = 3 x simple interest on principal + 3 x interest on simple interest + 1 x interest on interest on interest.

 

= 3 x (200) + 3 x (8) + 1 x 0.32 =600 + 24 + 0.32 = 624.32

 

 

 

The amount at the end of 3 years = 5000 + 624.32 = 5624.32

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

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