Aptitude - Questions & Answers

Aptitude - Arithmetic Online Quiz

Quiz

Following quiz provides Multiple Choice Questions (MCQs) related to Basic Arithmetic. You will have to read all the given answers and click over the correct answer. If you are not sure about the answer then you can check the answer using Show Answer button. You can use Next Quiz button to check new set of questions in the quiz.

Q 1 - Which term of 2,7, 12,17... is 87?

Answer : C

Explanation

  
Here a = 2,  d = 7 - 2 = 5,  
Let there be n term.  
Using formula T_n = a + (n - 1)d  
T_n = 2 + (n - 1) x 5 = 87  
=> 5n - 3 = 87  
=> n = 18

Q 2 - Find two natural numbers whose sum is 72 and the least common multiple is 429?

Answer : C

Explanation

  S
Sum x+y=72  
Lcm of 39 & 33 is 429

Q 3 - The least prime number is?

Answer : B

Explanation

2 is the least prime number.

Q 4 - The product of two successive positive integers is 462. Which is the smaller integer?

Answer : C

Explanation

  
 Suppose the two consecutive integers be y and y + 1 respectively.  According to question,       
 (y) x (y + 1) = 462  
 Or, y² + y - 462 = 0  
 Or, y² + 22y - 21y - 462 = 0  
 Or, y(y + 22) - 21(y + 22) = 0  
 Or, (y + 22) (y - 21) = 0  
 Or, y = 21

Q 5 - The number obtained by interchanging the digits of a two digit number is less than the original number by 18. If sum of the digits is 6, what was the original two digit number?

Answer : C

Explanation

  
 Let the original number be 10x + y.  
 Number obtained by interchanging the digits = 10y + x  
 ∴ (10x + y) - (10y + x) = 18  
 Or, x - y = 2 ... (i)  
 Also, x + y = 6 ... (ii)  
 From equations (i) and (ii), 
 x = 4 and y = 2.  
 ∴ Original number = (10 x 4) + 2 = 42

Q 6 - How many odd numbered pages are present in a book of 1089 pages?

Answer : D

Explanation

 
 Here pages are 1, 3, ..., 1089 which is an A.P. Here a = 1,  d = 2, l = 1089    
 Using formula T_n = a + (n - 1)d 
 T_n = 1 + (n - 1) x 2 = 1089 
 => 2n -1 = 1089 
 => n = 1090 / 2 = 545

Q 7 - Sum of three numbers in G.P. is 28 and there product is 512. What are the numbers?

Answer : C

Explanation

   
 let the numbers are a/r, a, ar  
 Then a/r x a x ar = 512  
 => a³ = 8³  
 gt; a = 8  
 Now a/r + a + ar = 28  
 => 8/r + 8 + 8r = 28  
 => 8/r + 8r = 20  
 => 2/r + 2r = 5  
 => 2r² + -5r + 2 = 0  
 => 2r² + -4r -r + 2 = 0  
 => 2r(r-2) - (r-2)=0  
 => (r-2)(2r-1) = 0  
 => r = 2 or r = 1/2  
 ∴ numbers are 4, 8, 16.

Q 8 - If population of a bacteria doubles every 2 minutes. In how much minutes, it will grow from 1000 to 512000?

Answer : D

Explanation

   
 Let the required growth be 1000, 2000, 4000,...512000.  
 Here, a = 1000, r = 2, T_n = 512000  
 Using formula T_n = ar^n-1 
 => 1000 x 2^n-1 = 512000  
 => 2^n-1 = 512 = 2⁹  
 => n - 1 = 9  => n = 10 
 ∴ time taken will be 2 x 9 = 18 minutes.

Q 9 - How many terms are present in A.P. 7, 11, 15, ..., 151?

Answer : A

Explanation

   
 Here a = 7,  d = 11 - 7 = 4,   
 Let there be n term.   
 Using formula T_n = a + (n - 1)d   
 T_n = 7 + (n - 1) x 4 = 151  
 => 4n + 3 = 151  
 => n = 37

Q 10 - Suman purchases N.S.C. every year whose value exceed s previous year's N.S.C by 500 Rs. In 10 years, she has bought N.S.Cs of 50000 Rs. What was the value of N.S.C. she bought in first year?

Answer : D

Explanation

   
 Let the required amount is a.  
 Also, d = 500, n = 10, S₁₀ = 50000  
 Using formula S₁₀ = (n/2)[2a + (n-1)d  
 => (10/2)[2a + (10-1)500] = 50000  
 => 5(2a + 9 x 500) = 50000  
 => 2a + 4500 = 10000  
 => a = 5500 / 2 = 2750

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