$4$ cards are drawn from a well-shuffled deck of $52$ cards. What is the probability of obtaining $3$ diamonds and one spade?
Number of ways of drawing $4$ cards from $52$ cards $=^{52} C_{4}$
In a deck of $52$ cards, there are $13$ diamonds and $13$ spades.
$\therefore$ Number of ways of drawing $3$ diamonds and one spade $=^{13} C_{3} \times^{13} C_{1}$
Thus, the probability of obtaining $3$ diamonds and one spade $ = \frac{{^{13}{C_3}{ \times ^{13}}{C_1}}}{{^5{C_4}}}$
If three letters can be posted to any one of the $5$ different addresses, then the probability that the three letters are posted to exactly two addresses is:
Twenty persons arrive in a town having $3$ hotels $x, y$ and $z$. If each person randomly chooses one of these hotels, then what is the probability that atleast $2$ of them goes in hotel $x$, atleast $1$ in hotel $y$ and atleast $1$ in hotel $z$ ? (each hotel has capacity for more than $20$ guests)
A fair dice is thrown up to $20$ times. The probability that on the $10^{th}$ throw, the fourth six apears is :-
Out of all possible $8$ digit numbers formed using all the digits $0,0,1,1,2,3,4,4$ a number is randomly selected. Probability that the selected number is odd, is-
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