NIELIT Scientific Assistant A 2020 November: 30

Question

Considering $5$ as the $1^{\text{st}}$  element in the sequence $\text{5, 11, 23, 47}$. What is the $6^{\text{th}}$  element in the sequence?

• A. $191$
• B. $172$
• C. $342$
• D. $106$

Answer 1

The pattern of the given series is as follows:

• $5*2+1=11$
• $11*2+1=23$
• $23*2+1=47$
• $47*2+1=95$
• $95*2+1=191$

So the 6^th  element will be $191$

Option (A) is correct.

Answer 2

Given that, $5,11, 23, 47,$ _____ , ______

We can do that, in this way,

• $5\overset{+6}{\rightarrow} 11$
• $11\overset{+12}{\rightarrow} 23$
• $23\overset{+24}{\rightarrow} 47$
• $47\overset{+48}{\rightarrow} 95$
• $95\overset{+96}{\rightarrow} 191$

So, the correct answer is $(A).$

Answer 3

A(191)

5--->11---->23---->47--->x---->y

Let's suppose y will be the 6th element

5----->23 (+18)

11----->47(+36)

23----->x (+72)     x=23+72=95

47----->y(+144)    y=47+144=191