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# Which term of the AP : 3, 8, 13, 18, . . . ,is 78?

**Solution:**

The formula for n^{th} term of an AP is aₙ = a + (n - 1) d

The given arithmetic progression is 3, 8, 13, 18, ...

First term: a = 3

Second term: a + d = 8

Common difference: d = 8 - 3 = 5

aₙ = a + (n - 1) d

aₙ = 78, n = ?

3 + (n - 1) 5 = 78

5(n - 1) = 78 - 3

n - 1 = 15

n = 16

78 is the 16^{th} term of the given AP.

**☛ Check: **NCERT Solutions for Class 10 Maths Chapter 5

**Video Solution:**

## Which term of the AP : 3, 8, 13, 18, . . . ,is 78?

NCERT Solutions Class 10 Maths Chapter 5 Exercise 5.2 Question 4

**Summary:**

78 is the 16^{th} term of the AP 3, 8, 13, 18, ...

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