Quantitative Aptitude - Arithmetic Ability Questions

Here in the given number series 49, 81, 121, 169, 196, 225

Except 196 all others are squares of odd numbers, whereas 196 is a square of 14 which is an even number.

Hence, the odd man in the given number series is 196.

There are two series, beginning respectively with 3 and 7. In one 3 is added and in another 2 is subtracted.

The next number is 1 - 2 = -1.

Let the numbers be x, x + 1, x + 2,  x + 3, x + 4, x + 5 and x + 6,

Then   (x + (x + 1) + (x + 2) + (x + 3) + (x + 4) + (x + 5) + (x + 6)) / 7 = 20.

or  7x + 21 = 140 or 7x = 119 or x =17.

Latest number = x + 6 = 23.

The given number series is 

3, 5, 8, 15, 28, 51, ?

Here the pattern it follows is

3

3 + 2 = 5 ( add prime number less than 3 i.e, 2)

5 + 3 = 8 (3 is prime number less than 5)

8 + 7 = 15 (7 is prime number less than 8)

15 + 13 = 28 (13 is prime number less than 15)

28 + 23 = 51 (23 is prime number less than 28)

51 + 47 = 98 (47 is prime number less than 51)

Hence, the next number in the given number series is 98.

Clearly, n(S) = (6 x 6) = 36.

Let E = Event that the sum is a prime number.

Then E= { (1, 1), (1, 2), (1, 4), (1, 6), (2, 1), (2, 3), (2, 5), (3, 2), (3, 4), (4, 1), (4,3),(5, 2), (5, 6), (6, 1), (6, 5) }

n(E) = 15.

P(E) = n(E)/n(S) = 15/36 = 5/12.

$$\begin{gathered} ?2 = 2×78-21+8+49-148 \\ = 57 - 21 \\ =36 \\ => ? = ±6 \end{gathered}$$

Let the number of correct answers be X.

Number of incorrect answers = (60 – X).

4x – (60 – x) = 130

=> 5x = 190 

=> x = 38