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Washington State Math Olympiad Hints and Solutions 2010 Grade 8 Probability and Statistics
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Problem |
1) A family has two children. At least one of them is a boy. What is the probability that both children are
boys?
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2) At the brand new middle school lockers open with PIN numbers instead of combination locks. PIN numbers consist of three one digit numbers and digits can repeat. This year all the 8th grade PIN numbers begin with the digits 6, 7, 8, or 9, but the other two can be any number from 0 up to 9. How big does the
8th grade class have to be to guarantee at least two students have the same PIN numbers?
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3)
Toni's teacher gives a 20 point quiz every Friday. On her first five quizzes Toni scores: 15, 4, 16, 18 , and
15. After the next two 20 point quizzes, her average on all seven quizzes is 15. What is the median?
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