Question

4. The first and last term of an A.P. are - 4
and 146. The sum of terın is 7171. The
number of terms is
(A) 100
(B) 101
(C) 102
(D) 99
​

Answer 1

Answer:

Given that,

a1 = -4, aN = 146

And Sn = 7171

We want to find number of terms (. i. e., n)

Sn = n/2 ( aN + a1)

7171 = n/2 ( 146 - 4)

7171 = n/2 × 142

7171 = n × 71

n = 7171 / 71

n = 101

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