Question

Which term of A.P 3,8,13,18. Will be 55more than its 20th term

Answer 1

Hi ,

3 , 8 , 13 , 18 , ... is an A. P

first term ( a ) = 3

common difference ( d ) = a2 - a1

d = 8 - 3

d = 5

20 th term in A.P = a20

a20 = a + 19d

= 3 + 19 × 5

= 3 + 95

= 98

55 more than a20 = 98 + 55 = 153

assume n th term of A.P = 153

a + ( n - 1 ) d = 153

3 + ( n - 1 ) 4 = 153

( n - 1 ) 4 = 153 - 3

( n - 1 ) = 150/4

n - 1 = 35

n = 35 + 1

n = 36

Required term is n = 36

I hope this helps you.

:)