Choose the correct answer in each of the following questions:

Question:

Choose the correct answer in each of the following questions:

How many two-digit numbers are divisible by 3?

(a) 25

(b) 30

(c) 32

(d) 36

Solution:

The two-digit numbers divisible by 3 are 12, 15, 18, ..., 99.

Clearly, these number are in AP.

Here, = 12 and d = 15 − 12 = 3

Let this AP contains n terms. Then,

$a_{n}=99$

$\Rightarrow 12+(n-1) \times 3=99 \quad\left[a_{n}=a+(n-1) d\right]$

$\Rightarrow 3 n+9=99$

$\Rightarrow 3 n=99-9=90$

$\Rightarrow n=30$

Thus, there are 30 two-digit numbers divisible by 3.

Hence, the correct answer is option is B.

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