Question

What is the value of X' in the sequence

2, 7, 22, 67, 202, X, 1822?

(a) 603

(b) 605

(c) 607

(d) 608

Answer 1

Correct option is (c) 607

1^st term = 2

2^nd term = 7 = 2 × 3 + 1

3^rd term = 22 = 7 × 3 + 1

we can write the pattern followed by the number in this series as

n^th number = (n - 1)^th number × 3 + 1

Therefore, X which is 6^th number in the series(n = 6) is

X = 202 × 3 + 1

= 607