Hi,
I am having trouble with this problem I know it might seem really simple but i dont understand how to calculate what the questions ask me.
Q:
The probabilty A hits a target is 1/3
The probabilty A hits a target is 1/5
They both fire at the same time.Find the probability of the following:
(i) A does not hit target
(ii) both A and B hit target
(iii) at least one of them hit target
(iv) Neither hit target.
This question comes down to understanding how combining probabilities work and how likelihood relates to unlikelihood. The probability of A not occurring is 1 minus the probability is does occur. If you want to know the chances of two events both occurring you multiply their chances together. At least one occurring is A or B occurring, so you add them. Neither occurring is the opposite of at least one occurring, so you take 1 minus the previous answer.
These seem difficult at first but it's really just applying a few concepts on combining probabilities.
Adding A and B for atleast 1 doesn't work, because they are both separate probabilities, unlike dice or a coin.
If you were looking for at least a 1, 2, or 3 on a dice, you would add all 3 probabilities together, so 1/6 + 1/6 + 1/6 = 1/2
However, this is more like the chance of it raining out, if you have a 75% chance that it will rain on days A and B, there's a (25%*25%) 12.5% chance that it won't rain either day, therefore a (1-.125) 87.5% chance that it will rain at least one day.