Quantitative Aptitude - Arithmetic Ability Questions

  4             3             4             7               15        ?
×1-1      ×1+1       ×2-1       ×2+1           ×3-1

15x3 - 1 = 45 - 1 = 44

Here the series follow the rule that

12+22 = 5

32+42 = 25

52+62 = 61

72+82 = 113

SO NEXT IS, 92+102 = 181

The series given follow the pattern

+2, +2+4, +2+4+6, +2+4+6+8, +2+4+6+8+10,...

Here ? = 7 + 2 + 4 = 13.

We have n(s) =52C2 52 = 52*51/2*1= 1326. 

Let A = event of getting both black cards 

     B = event of getting both queens 

A∩B = event of getting queen of black cards 

n(A) = 52*512*1 = 26C2 = 325, n(B)= 26*252*1= 4*3/2*1= 6  and  n(A∩B) = 4C2 = 1 

P(A) = n(A)/n(S) = 325/1326;

P(B) = n(B)/n(S) = 6/1326 and 

P(A∩B) = n(A∩B)/n(S) = 1/1326 

P(A∪B) = P(A) + P(B) - P(A∩B) = (325+6-1) / 1326 = 330/1326 = 55/221

52000 ÷ 40 ÷ 65 × 30 = ? - √400

(52000 ÷ 40) ÷ 65 × 30 = ? - 20

(1300 ÷ 65) × 30 = ? - 20

20 × 30 = ? - 20

600 = ? - 20

? = 620

Here the given number series is 6, 3, 3, 4.5, 10

The odd one in the given series is 10

The pattern it follows is

6

6 x 0.5 = 3

3 x  1  = 3

3 x 1.5 = 4.5

4.5 x 2 = 9

Hence, the odd number is 10.