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Three numbers are selected randomly between 1 to 20 . Then, the probability that they are consecutive numbers will be
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Verified Answer
The correct answer is:
$\frac{3}{190}$
Number of sample space for selecting three numbers between 1 to $20={ }^{20} C_{3}$
Number of ways that they are consecutive numbers $=18$.
$\therefore$ Required probability
$$
\begin{array}{l}
=\frac{18}{20} C_{3}=\frac{18 \times 3 \times 2}{20 \times 19 \times 18} \\
=\frac{3}{190}
\end{array}
$$
Number of ways that they are consecutive numbers $=18$.
$\therefore$ Required probability
$$
\begin{array}{l}
=\frac{18}{20} C_{3}=\frac{18 \times 3 \times 2}{20 \times 19 \times 18} \\
=\frac{3}{190}
\end{array}
$$
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