#### Question

Find the 20^{th} term from the last term of the A.P. 3, 8, 13, …, 253

#### Solution

Given A.P. is

3, 8, 13, …, 253

Common difference for this A.P. is 5.

Therefore, this A.P. can be written in reverse order as

253, 248, 243, …, 13, 8, 3

For this A.P.,

a = 253

d = 248 − 253 = −5

n = 20

a_{20} = a + (20 − 1) d

a_{20} = 253 + (19) (−5)

a_{20} = 253 − 95

a = 158

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

Is there an error in this question or solution?

Solution Find the 20th term from the last term of the A.P. 3, 8, 13, …, 253 Concept: nth Term of an AP.