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Probability question?
The question says: You are going to toss a coin repetedly in sucessive trials until you get a head for the first time, and then you are going to stop the experiment. Assuming that the coin is unbalanced with P(head)=1/5.
(1) Express the event "at least 4 tosses are required" in terms of the outcomes
(2)Compute the probabilities P ("at least 4 tosses are required before the experiment terminates")
(3) Explain why the probability calulated in (4) is large
Please help!
3 Answers
- PaulaLv 71 decade agoFavorite Answer
1. If at least 4 tosses are required, then the first 3 tosses are tails. So the event is P(1st 3 tosses are tails). I think that is what they mean.
2. P(1st 3 tosses are tails) = p(tail) x p(tail) x p(tail) = 4/5 x 4/5 x 4/5 = (4x4x4) / (5x5x5) = .... (I'll let you work out the actual number)
3. It is high because tails are much more likely than heads, so there is a fairly good chance that the first three tosses will be tails.
- 1 decade ago
I'm trying to figure out the same question. I would think it would be 1/2*1/2*1/2*1/2=P(TTTH). because if 4 tosses are required, no matter how many time you toss it the probability each time is going to be 1/2 right?
- unixmachineLv 41 decade ago
This is one of those classes where your grade looking back is always surprising.
