Mathematics
Answer
Two digit numbers which are divisible by 3 are 12, 15, 18, 21, ….. , 99.
The above series is an A.P. with first term = a = 12 and common difference = d = 15 - 12 = 3.
Let 99 be the nth term, we know that
an = a + (n - 1)d
∴ 99 = 12 + (n - 1) × 3
⇒ 99 = 12 + 3n - 3
⇒ 3n + 9 = 99
⇒ 3n = 90
⇒ n = 30.
Hence, Option 3 is the correct option.