Question

In the given series, 1.5, 0.5, -0.5, -1.5, .... , -8.5 If $n^{th}$ term is -8.5, find n.

• A. 10
• B. 12
• C. 11
• D. 9

Answer 1

The correct option is C

11

a = 1.5; d = 0.5 - 1.5 = -1

a + (n-1)d = -8.5

1.5 + (n-1)(-1) = -8.5

(n-1)(-1) = -10

n-1 = 10

n = 11