Find the probability that the shots were made by the first shooter

probability

One of the three shooters is called to the line of fire and makes two shots. The probability of hitting the target for the first shooter – 0.3, for the second – 0.5, and for the third – 0.8. The target is not hit. Find the probability that the shots were made by the first shooter.

The probability for the first shooter to be chosen is 1/3. The probability to miss 1 time is 0.7.

So the answer should be (1/3) * 0.7 * 0.7.
Do I make a mistake?

Best Answer

If the first shooter is selected, the probability of not hitting the target at all is $(1-0.3)^2=0.49$. The same probabilities for the second and third are $(1-0.5)^2=0.25$ and $(1-0.8)^2=0.04$. Then use the law of total probability to find the final answer as $$\frac{0.49}{0.49+0.25+0.04}=\frac{49}{78}$$