SOLUTION: your friend decides to flip a coin repeatedly to analyze whether the probability of a head on each flip is 1/2. He flips the coin 10 times and observes a head 7 times. He concludes

Question 761969: your friend decides to flip a coin repeatedly to analyze whether the probability of a head on each flip is 1/2. He flips the coin 10 times and observes a head 7 times. He concludes that the probability of a head for this coin is 7/10=.70.
a. Your friend claims that the coin is not balanced, since the probability is not .50. What's wrong with your friend's claim?
b. If the probability of flipping a head is actually 1/2, what would you have to do to ensure that the cumulative proportion of heads falls very close to 1/2?
Answer by ramkikk66(644) (Show Source): You can put this solution on YOUR website!
a) Every test of head or tail is *independent* of the previous tests. Hence, even if we got 7 heads in 10 tests, the 11th attempt still has a probability of getting heads as 1/2 (as though every test is the first test)
b) To reach very close to 1/2 you have to conduct a very large number of trials (ideally, toss the coin infinite number of times!)

:)

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