Quantitative Aptitude - Arithmetic Ability Questions

The given number series is 8, 16, 20, 36, 68

8

8 x 2 - 4 = 12 (NOT 16)

12 x 2 - 4 = 20

20 x 2 - 4 = 36

36 x 2 - 4 = 68

Hence, the odd man in the given series is 16.

Given number series is 61, 66, 83, 121, 185

Here the given series follows a pattern that,

$$\begin{gathered} 61 \\ 61 + 22 + 1 = 66 \\ 66 + 42 + 1 = 83 \\ 83 + 62 + 1 = 120 (not 121) \\ 120 + 82 + 1 = 185 \end{gathered}$$

Hence, the odd man in the given series is 121.

2(A+B+C)'s 1 day work = 1/30 + 1/24 + 1/20 = 1/8

=>(A+B+C)'s  1 day's work= 1/16

work done by A,B and C in 10 days=10/16 = 5/8

Remaining work= 3/8

A's 1 day's work= 116-124=148

Now, 1/48 work is done by A in 1 day.

 So, 3/8 work  wil be done by A in =48 x (3/8) = 18 days

The given number series 2, 19, 0, 21, –2, ? follows a pattern,

2

2 + 17 = 19

19 - 19 = 0

0 + 21 = 21

21 - 23 = -2

-2 + 25 = 23

Hence, the next number in the series is 23.

Age of the teacher = (37 * 15 - 36 * 14) years = 51 years.

16x + 85 = 17(x + 3)

x = 34 + 3 = 37