Set of portraits consists of 6 boys and 4 girls. Little brother drew mustache on three of these set portraits. What is the probability that a randomly selected image will be a portrait of a girl without a mustache?
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Hello, speculus!
Here's an explanation of Plato's excellent solution.
There are portraits of 6 boys and 4 girls.
Little brother drew mustaches on three of these portraits.
What is the probability that a randomly selected portrait
will be of a girl without a mustache?
Assume that little brother randomly chose three portraits to deface.
. . He has: . possible choices.
He has 4 choices for the genders of the subjects:
. .
. .
For each choice, there is a probability of choosing a girl without a mustache.
. .
Therefore: .
. . . . . . . . . . . . . . . . . . . . . .