Question:

If three cards are drawn randomly from a well-shuffled pack of \(52\) cards, then the probability that all the three bear a prime number is

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When cards are drawn without replacement, use combinations: \[ P=\frac{\binom{\text{favourable cards}}{r}} {\binom{\text{total cards}}{r}}. \] First count the required cards carefully, then apply combinations directly.
Updated On: Jul 9, 2026
  • \(\dfrac{35}{1105}\)
  • \(\dfrac{28}{1105}\)
  • \(\dfrac{21}{1105}\)
  • \(\dfrac{18}{1105}\) \bigskip
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The Correct Option is B

Solution and Explanation

Concept: The probability of an event is \[ P(E)=\frac{\text{Number of favourable outcomes}} {\text{Total number of outcomes}}. \] Since cards are drawn without replacement, combinations are used.

Step 1:
Count the cards bearing prime numbers. In a standard deck, the numbered cards are \[ 2,3,4,5,6,7,8,9,10. \] The prime numbers among them are \[ 2,\;3,\;5,\;7. \] Each occurs in \(4\) suits. Hence the total number of prime-numbered cards is \[ 4\times 4=16. \]

Step 2:
Find the number of favourable outcomes. To draw \(3\) cards, all bearing prime numbers, \[ \text{Favourable outcomes} = \binom{16}{3}. \] \[ = \frac{16\cdot15\cdot14}{3\cdot2\cdot1} = 560. \]

Step 3:
Find the total number of outcomes. The total number of ways of drawing \(3\) cards from \(52\) cards is \[ \binom{52}{3}. \] \[ = \frac{52\cdot51\cdot50}{3\cdot2\cdot1} = 22100. \]

Step 4:
Compute the probability. \[ P = \frac{\binom{16}{3}} {\binom{52}{3}} = \frac{560}{22100}. \] Dividing numerator and denominator by \(20\), \[ P = \frac{28}{1105}. \]

Step 5:
Write the final answer. \[ \boxed{\frac{28}{1105}} \]
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