How many terms are there in the series :

0.5, 0.53, 0.56, …….., 1.1 ?

Since, 0.53 - 0.5 = 0.03, 0.56 - 0.53 = 0.03.

Hence, the series is an A.P. with common difference = 0.03 and last term = 1.1.

n^th term of an A.P. is given by,

a_n = a + (n - 1)d

⇒ 1.1 = 0.5 + (n - 1) × 0.03

⇒ 1.1 = 0.5 + 0.03n - 0.03

⇒ 1.1 = 0.47 + 0.03n

⇒ 1.1 - 0.47 = 0.03n

⇒ 0.63 = 0.03n

⇒ n = 21.

Hence, no. terms in the series = 21.