When two coins are tossed simultaneously then the possible outcomes obtained are {HH, HT, TH, and TT}.
Here H denotes head and T denotes tail.
Therefore, a total of 4 outcomes obtained on tossing two coins simultaneously.
Number of favourable outcome(s) for no head is {TT}
Number of favourable outcome(s) for one head is {HT, TH}
Therefore, the event of getting at most one head has 3 favourable outcomes. These are TT, HT and TH.
Therefore, the probability of getting at most one head = 3/4.
