This is the Important question based on Arithmetic progression Chapter of R.S Aggarwal book for ICSE & CBSE

Board.

Here the AP and the last term of AP is given you have to find which term of the AP this must be.

This is the Question Number 9 Exercise 11 A of RS Aggarwal Solution.

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# Which term of the AP 3, 8, 13, 18, … is 88?

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Let

nth term is 88.AP is 3, 8, 13, 18, …

Here,

First term = a = 3

Common difference = d = 8 – 3 = 5

nth term of AP is a_n = a + (n – 1) d

Now,

88 = 3 + (n – 1)(5)

88 – 3 = (n – 1) x 5

n – 1 = 88 /5

or n = 17 + 1 = 18

Therefore: 88 is the 18th term.