Three coins are tossed at once. What is the probability of getting at least two tails?

When three coins are tossed at once, the sample space is {HHH, HHT, HTH, THH, TTH, THT, HTT, TTT}.

I.e., n(S) = 8

Let E be the event of getting at least two tails.

So, the favourable outcomes are {TTH, THT, HTT, TTT}

Thus, n(E) = 4

We know that the probability of an event = Number of favourable outcomes/Total number of outcomes.

Hence, the probability of getting at least two tails = 4/8 = ½.