Question:medium

P and Q play chess frequently against each other. Of these matches, P has won 80% of the matches, drawn 15% of the matches, and lost 5% of the matches.
If they play 3 more matches, what is the probability of P winning exactly 2 of these 3 matches?

Show Hint

When solving binomial probability problems, remember the formula \( P(X = k) = \binom{n}{k} p^k (1-p)^{n-k} \) and carefully calculate the combinations, probabilities, and powers.
  • \( \frac{48}{125} \)
  • \( \frac{16}{125} \)
  • \( \frac{16}{25} \)
  • \( \frac{25}{48} \)
Show Solution

The Correct Option is A

Solution and Explanation

The probabilities for the outcomes of a match involving P are defined as follows, based on the provided data:
\( P({Win}) = 0.80 \)
\( P({Draw}) = 0.15 \)
\( P({Loss}) = 0.05 \)
We are tasked with determining the probability of P achieving exactly 2 wins in a series of 3 matches. Given that each match's outcome is independent, this scenario aligns with a binomial probability calculation, specifically the probability of obtaining 2 successes in 3 trials.
The binomial probability formula is stated as:
\[P(X = k) = \binom{n}{k} p^k (1-p)^{n-k}\]In this context:
\(n = 3\) represents the total number of matches played.
\(k = 2\) denotes the desired number of wins.
\(p = 0.80\) is the probability of P winning a single match.
\(1 - p = 0.20\) is the probability of P not winning a single match.
The calculation for the probability of exactly 2 wins is:
\[P(X = 2) = \binom{3}{2} (0.80)^2 (0.20)^1 = 3 \times 0.64 \times 0.20 = \frac{48}{125}.\]Consequently, the definitive answer is \( \frac{48}{125} \).
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