Verbal Reasoning - Mental Ability Questions

The distance around a circle is called as Circumference. And that in the case of square or rectangle it is called as Perimeter.

We know that in A.P series
18th term = a + 17d
29th term = a + 28d
But given
a + 17d = 29..........(i)
a + 28d = 18......... (ii)
Solving equation (i) and (ii), we get
d = -1
put d = -1 in any of the above equations and we get,
a = 46
Now, we know 49th term can be written as, a + 48d
putting the value of a and d in the above equation,
a + 48d = 46 + 48(-1)
= 46 - 48
= -2

Hence, the 49th term is -2.

Multiplicative inverse is nothing but a reciprocal of a number. 

It is defined as one of a pair of numbers that when multiplied with another number equals the number 1.

Multiplicative inverse or reciprocal of 7 is 

7 x n = 1

=> n = 1/7.

Hence, Multiplicative inverse or reciprocal of 7 is  1/7.

The sequence in first column is x 5. Thus, 1 x 5 = 5,  5 x 5 = 25,  25 x 5 = 125.
The sequence in third column is x 2. Thus, 7x 2 = 14,  14 x 2 = 28,  28 x 2 = 56.
The sequence in second column is x 4.
.'. Missin number = 12 x 4 = 48.