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Coin Flip A fair quarter is flipped three times. For each of the following proba

ID: 3231448 • Letter: C

Question

Coin Flip A fair quarter is flipped three times. For each of the following probabilities, use the formula for the binomial distribution and a calculator to compute the requested probability. Next, look up the probability in Table 2 of the Appendix and compare the table result with the computed result. (a) Find the probability of getting exactly three heads. (b) Find the probability of getting exactly two heads. (c) Find the probability of getting two or more heads. (d) Find the probability of getting exactly three tails.

Explanation / Answer

(a) Pr(3 Heads) = Pr (X=3) = 3C3 (0.5)3 = 0.125

(b) Pr (exactly 2 heads) = Pr(X=2) = 3C2 (0.5)2(0.5) = 0.375

(c) Pr ( two or more heads) = Pr (X=2) + Pr (X=3) = 0.125 + 0.375 = 0.5

(d) Pr (exactly three tails) = Pr(X=0) = 3C0(0.5)3 (0.5)0 = 0.125