Quantitative Aptitude - Arithmetic Ability Questions

Here given series follows a pattern that

0.25, 8, 128, 1024, ?

0.25 x 32 = 8

8 x 16 = 128

128 x 8 = 1024

1024 x 4 = 4096

Given number series is 12  9  13.5  30.3  ?  341.7

Here the pattern followed by the series is

12 

12 x 0.75 = 9

9 x 1.5 = 13.5

13.5 x 2.25 = 30.3

30.37 x 3 = 91.12

91.12 x 3.75 = 341.71

Hence, the missing number in the sequence is 91.12.

Alternatively 23 is added and 17 is subtracted from the terms. So, 634 is wrong.

Here the given series is 1, 3, 6, 11, 20, 37, ??,

and the logic behind the series is

1 x 2 + 1 = 3

3 x 2 + 0 = 6

6 x 2 + (-1) = 11

11 x 2 + (-2) = 20

20 x 2 + (-3) = 37

37 x 2 + (-4) = 70

Hence, the next number in the given series is 70.

20% of a = b 

=> (20/100) * a = b 

 b% of 20 =(b/100) x 20 = [(20a/100)  / 100] x 20= 4a/100 = 4% of a.

1, 1 + 1² = 2, 2 + 2² = 6, 6 + 3² = 15, 15 + 4² = 31, 31 + 5² = 56, 56 + 6² = 92

Last number of given series must be 92 not 91.

Here, S = {1, 2, 3, 4, ...., 19, 20}.

Let E = event of getting a multiple of 3 or 5 = {3, 6 , 9, 12, 15, 18, 5, 10, 20}.

P(E) = n(E)/n(S) = 9/20.