Question

Find the chance of drawing 2 white balls in succession from a bag containing 5 red and 7 white balls, the ball first drawn not being replaced.

Answer 1

Consider the given events.
A = A white ball in the first draw
B = A white ball in the second draw

$$\begin{gathered} \mathrm{Now}, \\ P\left(A\right)=\frac{7}{12} \\ P\left(B/A\right)=\frac{6}{11} \\ \therefore \mathrm{Required}\mathrm{probability}=P\left(A\cap B\right)=P\left(A\right)\times P\left(B/A\right)=\frac{7}{12}\times \frac{6}{11}=\frac{7}{22} \end{gathered}$$