Question

Three different numbers are selected at random from the set A = {1, 2, 3, ---- 10}. The probability that the product of two of the numbers is equal to the third is

• A. $\frac{3}{4}$
• B. $\frac{1}{40}$
• C. $\frac{1}{8}$
• D. $\frac{1}{4}$

Answer 1

The correct option is B $\frac{1}{40}$

$n\left(s\right)={10}_{c_s};E=\left\{\right(10,5,2\left)\right(8,2,4\left)\right(6,2,3\left)\right\}$
$\therefore p\left(ϵ\right)=\frac{n\left(ϵ\right)}{n\left(s\right)}=\frac{3}{{10}_{c_3}}=\frac{1}{40}$