UPSC Aptitude-Analytical Contributed by Mathematics updated on Feb 2019
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NDA National Defence Academy Examination General Intelligence Part A April 2011 Original Question Paper with answers and detailed explanations

1.  If   9 3 9 = 12

8 2 8 = 12

6 3 6 = ?

(1) 8

(2) 9

(3) 5

(4) 12

(5) None of these

Ans :  (1)

Explanation :   9 ÷ 3 + 9 = 12

8 ÷ 2 + 8 = 12

6 ÷ 3 + 6 = 8

2.  If 62 + 51 = 16,  91 + 85 = 24,  53 + 82 = 12,  72 + 83 = 25, then 73 + 83 = ?

(1) 4

(2) 20

(3) 15

(4) 37

(5) None of these

Ans :  (2)

Explanation :   6 - 2 = 4;  5 - 1 = 4

Now  4 * 4 = 16

Similarly  4 * 5 = 20.

3.  Answer in a short-cut method: 709 + 333 + 222 + 111 + 99 + 88 + 77 + 66 + 55 + 44 + 33 + 22 + 11 + 1 = ?

(1) 3,001

(2) 1,034

(3) 1,997

(4) 1,871

(5) None of these

Ans :  (4)

Explanation :   709 + 111 + (3 + 2 + 1) + 11 (9 + 8 ... 1) + 1 = 1871

4.  Insert the missing number :

2    5    7

4    7    5

3    6    ?

(1) 12

(2) 4

(3) 9

(4) 6

(5) None of these

Ans :  (4)

Explanation :   (2 + 4) ÷  2 = 3

(5 + 7) ÷ 2 = 6

∴ (7 + 5) ÷ 2 = 6

5.  If 6 * 2 = 31,  8 * 4 = 42,  2 * 2 = 11,  6 * 6 = 33,  then  8 * 6 = ?

(1) 33

(2) 43

(3) 14

(4) 42

(5) None of these