JAMB Mathematics 2019 Paper

Concept:Probability is the number of favourable outcomes divided by the total number of possible outcomes.Explanation:When a fair coin is tossed 3 times, the total number of possible outcomes is $2^3 = 8$.They are: $\{HHH, HHT, HTH, HTT, THH, THT, TTH, TTT\}$.At least two heads means exactly 2 heads or 3 heads.The favourable outcomes are $HHH$, $HHT$, $HTH$, and $THH$.So the number of favourable outcomes is $4$.Thus, $P(\text{at least two heads}) = \frac{4}{8} = \frac{1}{2}$.Answer:$\frac{1}{2}$ $\quad$ (Option D).