Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Probability

Question:

Three natural numbers are taken at random from the set A= {x : 1 ≤ x ≤ 100, x ∈ N. then the probability of that AM of the number taken is 25

Options:

$\frac{{ }^{77} C_2}{{ }^{100} C_3}$

$\frac{{ }^{25} C_2}{{ }^{100} C_3}$

$\frac{{ }^{74} C_2}{{ }^{100} C_3}$

none of these

Correct Answer:

$\frac{{ }^{74} C_2}{{ }^{100} C_3}$

Explanation:

$x_1+x_2+x_3=75$

coefficient $x^{75}$ in $\left(x^1+x^2+....+x^{100}\right)^3={ }^{74} C_2$

Hence probability $=\frac{{ }^{74} C_2}{{ }^{100} C_3}$.