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 = 0.70.
a. Your friend claims that the coin is not balanced, since the probability is not 0.50. 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?