Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Probability

Question:

If three distinct numbers are chosen randomly from the first 100 natural numbers, then the probability that all three of them are divisible by both 2 and 3 is

Options:

$\frac{4}{25}$

$\frac{4}{35}$

$\frac{4}{33}$

$\frac{4}{1155}$

Correct Answer:

$\frac{4}{1155}$

Explanation:

A number will be divisible by both 2 and 3, if it is divisible by their 1.c.m. i.e. 6.

There are 16 numbers, in first 100 natural numbers, which are divisible by 6. Therefore, number of ways of selecting 3 numbers such that all of them are divisible by both 2 and 3 is ${^{16}C}_3$.

∴ Required probability=$\frac{^{16}C_3}{^{100}C_3}=\frac{16×15×14}{100×99×98}=\frac{4}{1155}$