The probability of getting 9 cards of the same suit in one hand at a game of bridge is:
4 × ¹³C₉ × ³⁹C₄ / ⁵²C₁₃
Total hands: 13 cards chosen from 52, i.e. \(\binom{52}{13}\).
Favourable hands (exactly 9 of one suit):
Choose the suit in \(\binom{4}{1}=4\) ways, pick 9 of its 13 cards in \(\binom{13}{9}\) ways, and fill the remaining 4 cards from the other 39 cards in \(\binom{39}{4}\) ways.
\[P = \dfrac{4 \times \binom{13}{9} \times \binom{39}{4}}{\binom{52}{13}}\]
This matches option (1).
The chance that a software engineer will debug an error X correctly is 80%. The chance that software with the error X will crash after the correct debugging is 30%. The chance of crash of the software by wrong debugging is 70%. A software with the error X crashed. The probability that its error was debugged correctly is:
A six faced die is a biased one. It is thrice more likely to show an odd number than to show an even number. It is thrown twice. The probability that the sum of the numbers in the two throws is even is
A coin is biased so that a head is twice as likely to occur as a tail, if the coin is tossed three times, what is the probability of getting exactly two tails?
From two well shuffled pack of cards what is the probability of getting one Jack from the first one and a King from the second?
If A is an event of getting 13 by throwing two unbiased six-faced dice, then A is called
One summer, Peter visits 4 villages (A, B, C and D) in a random order. Find the probability that he visits (i) A before B (ii) A before B and B before C respectively?