a bag contains 10 black and 16 white balls.22 balls are drawn one by one till 4 white balls remain in the bag.what is the probability the 22th ball drawn is black. all balls are distinct.
Hello, ayushdadhwal!
$\displaystyle \text{A bag contains 10 black and 16 white balls.}$
$\displaystyle \text{22 balls are drawn one by one untll 4 white balls remain in the bag.}$
$\displaystyle \text{What is the probability the 22th ball drawn is black.}$
$\displaystyle \text{All balls are distinct.}$ . Is this relevant?
I have a back-door approach to this problem.
I may be totally wrong, but I can't shake my reasoning.
. . . . . . . . . $\displaystyle \overbrace{\circ\;\bullet\;\bullet\;\circ\;\bullet \;\hdots\;\square}^{\text{10 black, 12 white}}\;|\;\circ\;\circ\;\circ\;\circ $
. . . . . . . . . . . . . . . . . . . . $\displaystyle \Uparrow$
What is the probability that this is black?
Isn't it .$\displaystyle \dfrac{10}{22} \:=\:\dfrac{5}{11}$ ?