Question

An arithmetic sequence has $6^{th}$ term as 52 and ${15}^{th}$ term as 142. Find a & d .

• A. 2, 10
• B. 10, 2
• C. 2, 20
• D. 20, 2

Answer 1

The correct option is A

2, 10

Given $a_6$ = a + (6 - 1) d = 52

a + 5d = 52 ---------------------(i)

and $a_{15}$ = a + (15 - 1) d = 142

a + 14d = 142 -----------------(ii)

equation (ii) – equation (i) $\Rightarrow$ 9d = 90

d = 10

Substituting d = 10 in (i)

a + 50 = 52

a = 2