Asked by carly
One member of the debate team is going to be chosen President. Each member is equally likely to be chosen. The probability that a girl is chosen is 2/3 the probability that a boy is chosen. If the debate team has 20 people, how many girls are there?
Answers
Answered by
Reiny
boys --- b
girls ---- g
b + g = 20 or g = 20-b
prob( boy is chosen) = b/20
prob(girl is chosen) = g/20
but g/20 = (2/3)(b/20
g/20 = b/30
3g = 2b
3(20-b) = 2b
60 - 3b = 2b
5b = 60
b = 12
so 12 boys and 8 girls
girls ---- g
b + g = 20 or g = 20-b
prob( boy is chosen) = b/20
prob(girl is chosen) = g/20
but g/20 = (2/3)(b/20
g/20 = b/30
3g = 2b
3(20-b) = 2b
60 - 3b = 2b
5b = 60
b = 12
so 12 boys and 8 girls
Answered by
oobleck
for every 2 girls, there are 3 boys to choose from
2/5 of 20 is 8
2/5 of 20 is 8
Answered by
bob
8 is right
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