In a class of 16 girls and 20 boys, a pupil is selected at random.

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a) Find the probability that the pupils selected is a boy!

b) If the boy selected leaves the class and a second pupils dan then selected at random, find the probability that the pupil selected is a girl!​

In a class of 16 girls and 20 boys, a pupil is selected at random.

Penjelasan dengan langkah-langkah:

Sample size (nS) = 16 + 20 = 36

number of boy (nB) = 20

number of girl (nG) = 16

a)

Probably of boy being selected:

p(boy) = frac{nb}{ns}

= frac{20}{36}

= frac{5}{9}

= 0.556

b) if the selected boy leaves then, the sample size will be

ns = 16 + 19 = 35

therefore,

p(girl) = frac{ng}{ns}

= frac{16}{35}

= 0.46