# Find the 20^{th} term from the last term of the AP : 3, 8, 13, . . ., 253.

**Solution:**

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

Here, aₙ is the n^{th} term, a is the first term, d is the common difference and n is the number of terms.

Given A.P. is 3, 8, 13, ..., 253

As the 20^{th} term is considered from last, so a = 253

Common difference, d = 3 - 8 = - 5 (Considered in reverse order)

We know that the n^{th} term of an A.P. is aₙ = a + (n - 1) d

So, 20^{th} Term is a₂₀ = a + (20 - 1)d

a₂₀ = 253 + (20 - 1)(- 5)

= 253 - 19 × 5

= 253 - 95

= 158

20^{th} term from the last term is 158.

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

**Video Solution:**

## Find the 20^{th} term from the last term of the AP : 3, 8, 13, . . ., 253

Class 10 Maths NCERT Solutions Chapter 5 Exercise 5.2 Question 17

**Summary:**

The 20^{th} term from the last term of the A.P. 3, 8, 13,....., 253 is 158.

**☛ Related Questions:**

- Fill in the blanks in the following table, given that a is the first term and d is the Common difference, and an-the nth term of the AP.adnan7 38…….- 18……..100…….-318-5-18. 92.5……. 3.63.5 0105…….
- Choose the correct choice in the following and justify:i) 30th term of the AP: 10, 7, 4……. isa) 97 b) 77 c) - 77 d) - 87ii) 11th term of AP: -3, - 1/2, 2 is:a) 28 b) 22 c) - 38 d) - 48 (1/2)
- In the following AP, find the missing terms in the boxes: i) 2, _, 26 ii) _, 13, _ , 3 iii) 5, _ , _ , 9 ½ iv) - 4, _ , _ , _ , _ , 6 v) _ , 38, _ , _ , _ , - 22.
- Which term of the AP: 3, 8, 13, 18……. is 78.

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