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Aptitude - Arithmetic Online 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 - What is the 105^th term of A.P. 4, 4.5, 5, 5.5 ... ?

Answer : A

Explanation

Here a = 4, d = 4.5 - 4 = 0.5, n = 105 
Using formula T_n = a + (n - 1)d 
T₁₀₅ = 4 + (105 - 1) x 0.5 
= 56

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 - If 3^X-1 +3^X+1 = 270, then X=?

Answer : D

Explanation

  
 3^{X-1^{+3^X+1 = 270  
 => 3^X(3^-1+3¹) = 270  
 => 3^X x (10/3) = 270  
 => 3^X-1 = 270/10 
 = 27 
 =3³  
 => X-1=3  
 => X=4}}

Q 4 - The difference between 58% and 39% of a number is 247. What is 62% of that number?

Answer : B

Explanation

  
 Let the number be y.  
 According to question,       (58 - 39)% of y = 247  
 Or, y x (19/100) = 247  
 Or, y = 1300  
 ∴62% of 1300 = (62/100) x 1300 = 806

Q 5 - How many 3-digits numbers are there which are completely divisible by 6?

Answer : B

Explanation

 
 Here numbers are 102, 108, ..., 996 which is an A.P. 
 Here a = 102,  d = 108 - 102 = 6,    
 Using formula T_n = a + (n - 1)d    
 T_n = 102 + (n - 1) x 6 = 996    
 => 96 - 6n = 996   
 => n = 900 / 6 
 = 150

Q 6 - What is the sum of 1 + 2 + ... + 100 + 99 + ...1?

Answer : D

Explanation

 
 Given sequence = 2(1 + 2 + ... 99) + 100 
 Using formula S_n = (n/2)(a + l) 
 Required sum = 2 x (99/2)(1+99) +100 
 = 2 x 4950 + 100 
 = 9900 + 100 = 10000

Q 7 - What is the sum of (1 + 1/2 + 1/4 + ...)?

Answer : A

Explanation

  
 This is an infinite G.P. with a = 1 and r = 1/2.  
 Sum of infinite G.P. = a/(1-r)  = 1/(1-1/2)  = 1/(1/2)  = 2

Q 8 - 14² + 15² ... + 30² = ?

Answer : D

Explanation

  
 Using formula  (1² + 3² ... +  n²) = [n(n+1)(2n+1)]/6  
 14² + 15² ... + 30² = (1² + 2² ... + 30²) - (1² + 2² ... + 13²)  
 = (30 x 31 x 61)/ 6 - (13 x 14 x 27) / 6  
 = 9455 - 819  = 8636

Q 9 - Which term of 2, 7, 12, 17... is 92?

Answer : D

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 = 92  
 => 5n - 3 = 92  
 => n = 19

Q 10 - If n^th term of the series 72, 63, 54, ... is 9. What is n?

Answer : A

Explanation

   
 Here a = 72,  d = 63 - 72 = -9,    
 Using formula T_n = a + (n - 1)d    
 T_n = 72 + (n - 1) x -9 = 9    
 => 81 - 9n = 9   
 => n = 8

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