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MHT CET · Maths · Permutation Combination

Three numbers are selected randomly between 1 to 20 . Then, the probability that they are consecutive numbers will be

  1. A \(\frac{7}{190}\)
  2. B \(\frac{3}{190}\)
  3. C \(\frac{5}{190}\)
  4. D \(\frac{1}{3}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(\frac{3}{190}\)

Step-by-step Solution

Detailed explanation

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
\(=\frac{18}{20} C_{3}=\frac{18 \times 3 \times 2}{20 \times 19 \times 18}\)
\(=\frac{3}{190}\)