probability
posted by Sakura1 .
urgent till 3 pm i have in colombia¡
1 Alice has five coins in a bag: two coins are normal (i.e., fair with one face Heads and the other face Tails), two are doubleheaded (i.e., both sides are Heads), and the last one is doubletailed (i.e., both sides are Tails). She reaches into the bag and randomly pulls out a coin, with each coin being equally likely to be selected. Without looking at the coin she drew, she tosses it once.
What is the probability that the side of the coin that lands facedown is Heads?
2 The coin lands and shows Heads faceup. Given this information, what is the probability that the facedown side is also Heads?
3Alice discards the coin used in the first round. She knows that it showed Heads faceup but does not look at the other side of the coin. She reaches again into the bag and draws out a second coin from the 4 remaining coins, with each coin equally likely to be selected. Again, without looking at this second coin, she tosses it once. Given her knowledge of the result of the first coin toss (i.e., that it landed Heads faceup), what is the probability that this second coin toss results in Heads faceup?

1.) 3/5
2.) 2/3
3.) 13/24