Statistics probability help: 3 teenagers take a pass/fail driving test

jlt045

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My question says that 3 teenagers take a driving test, and each exam was pass or fail. I have determined that the first part is probability of all 3 passing, and it is 1/, or 0.125. but the next part says that nationwide, only 70% of teens pass, so if they were chosen randomly, what is the probability that all 3 will pass based on that. I have no idea how to determine this
 
My question says that 3 teenagers take a driving test, and each exam was pass or fail. I have determined that the first part is probability of all 3 passing, and it is 1/, or 0.125. but the next part says that nationwide, only 70% of teens pass, so if they were chosen randomly, what is the probability that all 3 will pass based on that. I have no idea how to determine this

Please quote the entire problem as given to you. Words matter a lot in probability problems.

The first part is only 1/8 (which I think you meant) if each passes or fails randomly and independently, with probability 1/2 to pass. This is because P(first passes AND second passes AND third passes) = P(first passes)*P(second passes)*P(third passes). If you don't know the probability for an individual passing, then you just have to say "Not enough information".

The second part is solved the very same way, but with 70% in place of 1/2. Give it a try.
 
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