Question

Series A: 2,5, 17,71, ......; Series B: 1, a, b, c, ...... What will replace the symbol c ?
(a) 70
(b) 11
(c) 47
(d) 36
(e) 27
dh

Answer 1

2*2 + 1 = 5

5*3 + 2 = 17

17*4 +  = 71

So

1*2 + 1 =3   =  a

3*3+ 2 = 11   = b

11*4 + 3 = 47   = c

47 is your answer

Answer 2

47 will replace the symbol c.

Answer - (Option C)

Given:

Series A: 2,5, 17,71, ......;

Series B: 1, a, b, c, ......  

To find : the equivalent of symbol c  

Solution :  

In series A,

2 $\times$ 2 + 1 = 5

5 $\times$ 3 + 2 = 17

17 $\times$ 4 + x = 71

X = 3  Hence,  

1 $\times$  2 + 1 = 3 = a

3 $\times$ 3 + 2 = 11 = b

11 $\times$  4 + 3 = 47 = c

C = 47.

Result:

47 will replace the symbol c.