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 - What is the 12^th term of A.P. 14, 9, -1, -6 ... ?

Answer : B

Explanation

Here a = 14, d = 9 - 14 = -5, n = 12 
Using formula T_n = a + (n - 1)d 
T₁₂ = 14 + (12 - 1) x -5 
= -41

Q 2 - How many numbers from 29 to 98 are exactly divisible by 9?

Answer : A

Explanation

  
29/9 = 3 and 98/9 = 10  
=> 10 - 3 =7.

Q 3 - How many digits are required to write numbers between 1 to 50?

Answer : B

Explanation

  
 1 to 9       ------ 9 digits  
 10 to 50   ------ 82 digits

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 - How many multiples of 3 are available between 15 and 105 including both?

Answer : B

Explanation

 
 Here numbers are 15, 18, ..., 105 which is an A.P. 
 Here a = 15,  d = 3,    
 Using formula T_n = a + (n - 1)d    
 T₁₁ = 15 + (n - 1) x 3 = 105 
 => 12 + 3n = 105 
 => n = 93 / 3 = 31

Q 6 - 45 + 46 + 47 + ... + 114 + 115 = ?

Answer : D

Explanation

 
 Here numbers are 45, 46, ..., 115 which is an A.P. Here a = 45,  d = 1, l = 115    
 Using formula T_n = a + (n - 1)d 
 T_n = 45 + (n - 1) x 1 = 115 
 => 44 + n = 116 
 => n = 116 - 44 = 71 
 Now Using formula S_n = (n/2)(a + l)  
 ∴ Required sum = (71/2)(45+115)  = 71 x 80  = 5680

Q 7 - Which term of 5, 10, 20, 40,.... is 1280?

Answer : B

Explanation

  
 Here numbers are in G.P.  Here a = 5,  r = 2, l = 1280. 
 Using formula T_n = ar^{n- 1} 
 T_n = 5 x 2^(n-1) = 1280  
 =2^(n-1) = 256  
 =2^(n-1) 
 = 2⁸  
 => n - 1 = 8  => n = 9

Q 8 - 1² + 2² ... + x² = [x(x+1)(2x+1)]/6. What is 1² + 3² +... + 19²?

Answer : A

Explanation

  
 (1² + 3² ... + 19²)  = (1² + 2² ... + 19²) - (2² + 4² ... + 18²)  
 Using formula  (1² + 3² ... +  n²) = [n(n+1)(2n+1)]/6  [19(19+1)(38+1)]/6 - (1 x 2² +  2² x 2² + 2² x  3² + ... + 2² x  9²)  
 = 2470 - 2²(1² + 2² + ... + 9²)  
 = 2470 -  (4 x 9 x 10 x 19)/6  
 = 2470 - 1140  
 = 1330

Q 9 - If an A.P. have 4^th term as 16 and 12^th term as 80. What will be its common difference?

Answer : C

Explanation

  
 Let's have first term as a, common difference is d then  
 a + 3d = 15 ... (i)  
 a + 11d = 80 ... (ii)  
 Subtracting (i) from (ii)  
 => 8d = 64  
 => d = 8

Q 10 - If 1² + 2² ... + 20² = 2870. What is 2² + 4² +... + 40²?

Answer : C

Explanation

   
 (2² + 4² ... + 40²)  = (1 x 2² + 2² x 2² + 3² x 2² +... +  20² x 2²)  
 = 2²(1² + 2² + .... + 20²) 
 = 4 x  385  
 = 1540

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