I'm tutoring 8th graders on probabilities and found the following problem on a worksheet:
Bob has a paper bag with 4 blue chips, 3 white chips, and 2 red chips. Assuming that each chip is drawn at
random, find the following probabilities.
(With replacement):
P(white, then white)
I am figuring there is a 3/9 probability that you will draw a white chip from the bag. Replacing the chip and drawing again, there is also a 3/9 probability. Reducing the fractions I am coming up with 1/3 x 1/3 = 1/9.
But I'm looking at a key that gives the answer at 2/27.
I'm not sure if I'm doing something wrong, or if the key is wrong.
Can anyone help?
Bob has a paper bag with 4 blue chips, 3 white chips, and 2 red chips. Assuming that each chip is drawn at
random, find the following probabilities.
(With replacement):
P(white, then white)
I am figuring there is a 3/9 probability that you will draw a white chip from the bag. Replacing the chip and drawing again, there is also a 3/9 probability. Reducing the fractions I am coming up with 1/3 x 1/3 = 1/9.
But I'm looking at a key that gives the answer at 2/27.
I'm not sure if I'm doing something wrong, or if the key is wrong.
Can anyone help?
via International Skeptics Forum https://ift.tt/sJPCVry
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