Question

Three unbiased coins are tossed together what is the probability of getting atmost 2 heads

Answer 1

3 coins could land in any of these ways:  HHH HHT  HTH  THH  TTH  THT  HTT  TTT  Those that have at least 2 heads are shown below:  HHH, HHT, HTH, THH <= that's 4 of 8 for a 50% or 1/2 probability  The probability of having at most 2 heads is 7/8, based on these choices:  HHT, HTH, THH, TTH, THT, HTT, TTT <= That's 7 of 8 or 87.5%