…Then a second marble is drawn.
1. What is the probability of selecting a purple marble and then a white marble?
2. What is the probability of selecting two white marbles?
3. Is there a greater chance of selecting two white marbles in a row or two purple marbles in a row?
Don’t just tell me how to do it, give me some numbers please
2 Answers
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All of these questions depend on the answer of what color marble was drawn first if it’s not replaced…that changes variables in determining the probability of the second event
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1. The probability of selecting a purple marble is (# of purple marbles) / (total # of marbles).
The probability of selecting a white marble is (# of white marbles) / (total # of marbles).
After you draw the purple marble on the first draw, since you don’t replace it, the total # of marbles has changed.
Probability of both of these things happening = product of the probabilities.
2. Probability of drawing a white marble on the first draw = (# of white marbles) / (total # of marbles).
Probability of drawing a white marble on the second draw = (# of white marbles) / (total # of marbles).
Probability of both of these things happening = product of the probabilities.
After you draw a white marble on the first draw, both the # of white marbles and the total # of marbles for the second draw have changed. So those two probabilities are not the same.
3. Evaluate the probability of two purple marbles the way I did two white marbles.
Compare the two numbers.
