Question 19

waecmaths question: 

There are 8 boys and 4 girls in a lift, What is the probability that the first person who steps out of the lift will be a boy

Option A: 

$\frac{3}{4}$

Option B: 

$\frac{1}{3}$

Option C: 

$\frac{2}{3}$

Option D: 

$\frac{1}{4}$

waecmaths solution: 

$\begin{align}  & no\text{ }of\text{ }boys\text{ }=8 \\ & no\text{ }of\text{ }girls\text{ }=4 \\ & \Pr (x)=\frac{no\text{ }of\text{ }\exp ected\text{ }outcome}{no\text{ }of\text{ }total\text{ }outcome} \\ & \Pr (boys)=\frac{8}{12}=\frac{2}{3} \\\end{align}$

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