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Problem 1:
- a. Probability of two red cubes: (12/18) × (11/17) = 132/306 = 22/51
- b. Probability of at least one green cube: 1 - P(two red) = 1 - 22/51 = 29/51
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Problem 2:
- a. Given first is girl, probability second is girl: 9/29
- b. Probability a girl and boy are chosen: P(GB) + P(BG) = (10/30)(20/29) + (20/30)(10/29) = 400/870 = 40/87
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Problem 3:
- a. Given first nail is small, probability second is small: 4/199
- b. Probability all three nails are too small: (5/200) × (4/199) × (3/198) = 60/7880400 = 1/131340
- c. Probability only the second nail is too small: (195/200) × (5/199) × (194/198) = 189150/7880400 = 6305/262680
Parent Tip: Review the logic above to help your child master the concept of probability without replacement worksheet.
