If the numbers divisible by 3, from 1 to 30, are arranged in descending order, which number will be at the 7th place from the bottom?

Correct option is D

Given:

The numbers divisible by 3, from 1 to 30.

Formula Used:

nth term in AP = a +(n-1)d

Solution:

A P according to question = 3,6,9-------30

According to question 7th from bottom 

Last  term in AP = a +(n-1)d =30

a =3 first term

d =3 all are multiple of 3

7th from bottom when AP is descending    = 7th from top when AP is ascending 

So 7th term = 3 +(7-1)3=21