SOLUTION: Mr. Johnson has nine brown-eyed and three blue-eyed brunettes in his fourth grade class. He also has two blue-eyed and three brown-eyed children with black hair. A child is selecte
Algebra ->
Customizable Word Problem Solvers
-> Misc
-> SOLUTION: Mr. Johnson has nine brown-eyed and three blue-eyed brunettes in his fourth grade class. He also has two blue-eyed and three brown-eyed children with black hair. A child is selecte
Log On
Question 1135844: Mr. Johnson has nine brown-eyed and three blue-eyed brunettes in his fourth grade class. He also has two blue-eyed and three brown-eyed children with black hair. A child is selected at random. What is the probability that the child has brown eyes given that he or she is a brunette? Found 2 solutions by greenestamps, ikleyn:Answer by greenestamps(13200) (Show Source):
The brunettes are 9 with brown eyes and 3 with blue eyes, a total of 12. If a randomly chosen child is brunette, the probability that it has brown eyes is 9/12, or 3/4.
There are two (TWO) groups of students under the consideration.
First group (let's call it A) consists of nine brown-eyed and three blue-eyed brunettes.
Second group (let's call it B) consists of two blue-eyed and three brown-eyed children with black hair.
Since the chosen student is a brunette, it means that he (or she) was chosen among the group A.
The probability to choose a child with brown eyes among the group A is = = = 0.75 = 75%. ANSWER
