Question Number 139697 by otchereabdullai@gmail.com last updated on 30/Apr/21
$$\mathrm{In}\:\mathrm{an}\:\mathrm{entrance}\:\mathrm{examination}\:\mathrm{each}\: \\ $$$$\mathrm{question}\:\mathrm{has}\:\mathrm{four}\:\mathrm{possible}\:\mathrm{answers}. \\ $$$$\mathrm{A}\:\mathrm{candidate}\:\mathrm{answers}\:\mathrm{three}\:\mathrm{question} \\ $$$$\mathrm{by}\:\mathrm{guessing}\:. \\ $$$$\mathrm{a}.\:\mathrm{find}\:\mathrm{the}\:\mathrm{probability}\:\mathrm{that}\:\mathrm{all}\:\mathrm{three}\: \\ $$$$\mathrm{questions}\:\mathrm{are}\:\mathrm{wrong}. \\ $$$$\mathrm{b}.\:\mathrm{find}\:\mathrm{the}\:\mathrm{probability}\:\mathrm{that}\:\mathrm{all}\:\mathrm{the}\: \\ $$$$\mathrm{questions}\:\mathrm{are}\:\mathrm{correct}. \\ $$
Answered by mr W last updated on 30/Apr/21
$${a}. \\ $$$${p}=\frac{\mathrm{3}×\mathrm{3}×\mathrm{3}}{\mathrm{4}×\mathrm{4}×\mathrm{4}}=\frac{\mathrm{27}}{\mathrm{64}} \\ $$$${b}. \\ $$$${p}=\frac{\mathrm{1}×\mathrm{1}×\mathrm{1}}{\mathrm{4}×\mathrm{4}×\mathrm{4}}=\frac{\mathrm{1}}{\mathrm{64}} \\ $$
Commented by otchereabdullai@gmail.com last updated on 30/Apr/21
$$\mathrm{Prof}\:\mathrm{W}\:\mathrm{you}\:\mathrm{are}\:\mathrm{supper}! \\ $$