Q17 of 49 Page 105

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

a = 3, d = 5


Now, 253 = a + (n + 1) d


⇒ 253 = 3 + (n -1) x 5


⇒ 253 = 3 + 5n – 5 = – 2


⇒ 5n = 253 + 2 = 255


⇒ n = 255/5 = 51


Therefore, 20th term from the last term = 51 – 19 = 32


a32 = a + 31d


= 3 + 31 x 5


= 3 + 155 = 158


Thus, required term is 158


More from this chapter

All 49 →
15

For what value of n, are the nth terms of two APs: 63, 65, 67, . . . and 3, 10, 17, . . . equal?

 16

Determine the AP whose third term is 16 and the 7th term exceeds the 5th term by 12.

 18

The sum of the 4th and 8th terms of an AP is 24 and the sum of the 6th and 10th terms is44. Find the first three terms of the AP.

 19

SubbaRao started work in 1995 at an annual salary of Rs 5000 and received an incrementof Rs 200 each year. In which year did his income reach Rs 7000?