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

Answer: (B)

$\frac{187}{190}$

Answer 2

When we select three consecutive numbers from $1$ to $20$. There are $18$ possible combinations (i.e., 1,2,3; 2,3,4,.......; 18,19,20\\}