Question

Three numbers are chosen from $1$ to $20$. Find the probability that they are not consecutive.

• A. $\frac{186}{190}$
• B. $\frac{187}{190}$
• C. $\frac{188}{190}$
• D. $\frac{18}{{}^{20}{C}_3}$

Answer 1

The correct option is B $\frac{187}{190}$

Probability that they are

consecutive is $\frac{3}{190}$

Now, the probability of non

consecutive is

1 - (Probability of consecutive form )

$\Rightarrow 1-\frac{3}{190}$

$\Rightarrow \frac{187}{190}$