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Question Number 112163 by bobhans last updated on 06/Sep/20

In a class of 30 pupils , 12 are girls and   2 of them are short−sighted. Among   18 boys , 6 are short−sighted . If a pupil  is selected at random, what is the probability  that the pupil chosen will be    { (((a) a girls)),(((b) short−sighted)),(((c) a short−sighted boy)) :}

$$\mathrm{In}\:\mathrm{a}\:\mathrm{class}\:\mathrm{of}\:\mathrm{30}\:\mathrm{pupils}\:,\:\mathrm{12}\:\mathrm{are}\:\mathrm{girls}\:\mathrm{and}\: \\ $$$$\mathrm{2}\:\mathrm{of}\:\mathrm{them}\:\mathrm{are}\:\mathrm{short}−\mathrm{sighted}.\:\mathrm{Among}\: \\ $$$$\mathrm{18}\:\mathrm{boys}\:,\:\mathrm{6}\:\mathrm{are}\:\mathrm{short}−\mathrm{sighted}\:.\:\mathrm{If}\:\mathrm{a}\:\mathrm{pupil} \\ $$$$\mathrm{is}\:\mathrm{selected}\:\mathrm{at}\:\mathrm{random},\:\mathrm{what}\:\mathrm{is}\:\mathrm{the}\:\mathrm{probability} \\ $$$$\mathrm{that}\:\mathrm{the}\:\mathrm{pupil}\:\mathrm{chosen}\:\mathrm{will}\:\mathrm{be}\: \\ $$$$\begin{cases}{\left(\mathrm{a}\right)\:\mathrm{a}\:\mathrm{girls}}\\{\left(\mathrm{b}\right)\:\mathrm{short}−\mathrm{sighted}}\\{\left(\mathrm{c}\right)\:\mathrm{a}\:\mathrm{short}−\mathrm{sighted}\:\mathrm{boy}}\end{cases} \\ $$

Answered by MJS_new last updated on 06/Sep/20

(a) ((12)/(30))=(2/5)  (b) (8/(30))=(4/(15))  (c) (6/(30))=(1/5)

$$\left({a}\right)\:\frac{\mathrm{12}}{\mathrm{30}}=\frac{\mathrm{2}}{\mathrm{5}} \\ $$$$\left({b}\right)\:\frac{\mathrm{8}}{\mathrm{30}}=\frac{\mathrm{4}}{\mathrm{15}} \\ $$$$\left({c}\right)\:\frac{\mathrm{6}}{\mathrm{30}}=\frac{\mathrm{1}}{\mathrm{5}} \\ $$

Commented by bobhans last updated on 06/Sep/20

hihihi....thank you

$$\mathrm{hihihi}....\mathrm{thank}\:\mathrm{you} \\ $$

Commented by MJS_new last updated on 06/Sep/20

...after this hard job I need a break ��

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