Class - boys and girls

In the class are 60% boys and 40% girls. Long hair has 10% boys and 80% girls.

a) What is the probability that a randomly chosen person has long hair?
b) The selected person has long hair. What is the probability that it is a girl?

Correct result:

p1 =  0.38
p2 =  0.842

Solution:

p1=0.10.6+0.80.4=0.38p_1 = 0.1\cdot 0.6 + 0.8\cdot 0.4 = 0.38
p2=0.80.4/p1=0.842p_2 = 0.8\cdot 0.4 / p_1 = 0.842



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