Three unbiased coins are tossed simultaneously. Find the probability of getting:
(a) exactly two tails
(b) at least one head
(c) at most two heads

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Accepted Answer

Step 1: Possible outcomes are HHH, HHT, HTH, HTT, THH, THT, TTH, TTT. Total $= 8$.
(a) P(exactly two tails) $= \frac{3}{8}$ (HTT, THT, TTH)
Step 2: (b) P(at least one head) $= \frac{7}{8}$ (all except TTT)
Step 3: (c) P(at most two heads) $= \frac{7}{8}$ (all except HHH)

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