Two groups are competing for the positions on the board of directors of a corporation. The probabilities that the first and the second groups will win are 0.6 and 0.4, respectively. Further, if the first group wins, the probability of introducing a new product is 0.7, and when the second groups win, the corresponding probability is 0.3. Find the probability that the new product introduced was by the second group.
Two groups are competing for the positions on the board of directors of a corporation. The probabilities that the first and the second groups will win are 0.6 and 0.4, respectively. Further, if the first group wins, the probability of introducing a new product is 0.7, and when the second groups win, the corresponding probability is 0.3. Find the probability that the new product introduced was by the second group.

Let F : First group
S : Second group
N : Introducing a new product
We want to find P(S \mid N), i.e. new product introduced by the second group
\begin{array}{l} \mathrm{P}(\mathrm{S} \mid \mathrm{N})=\frac{\mathrm{P}(\mathrm{S}) \cdot \mathrm{P}(\mathrm{N} \mid \mathrm{S})}{\mathrm{P}(\mathrm{S}) \cdot \mathrm{P}(\mathrm{N} \mid \mathrm{S})+\mathrm{P}(\mathrm{F}) \cdot \mathrm{P}(\mathrm{N} \mid \mathrm{F})} \\ =\frac{(0.4)(0.3)}{(0.6)(0.7)+(0.4)(0.3)} \\ =\frac{0.12}{0.54} \\ =\frac{2}{9} \end{array}
Conclusion: Therefore, the probability of the second group introduced a new product is \frac{2}{9}