bponfgtr Posted January 1, 2017 Share Posted January 1, 2017 (edited) I need help understanding how this problem is done... Suppose there are 9 blue marbles, 4 yellow marbles and 10 green marbles in a box. What is the probability of randomly selecting three green marbles with replacement? Show fractions (don't have to simplify final fraction) and then round to 4 decimal places. tampa bucs I don't even know where to begin. Edited January 1, 2017 by bponfgtr Quote Link to comment Share on other sites More sharing options...
MarkT Posted January 3, 2017 Share Posted January 3, 2017 http://homepages.math.uic.edu/~bpower6/stat101/probability%20examples.pdf Quote Link to comment Share on other sites More sharing options...
Monica_in_Switzerland Posted January 3, 2017 Share Posted January 3, 2017 With replacement are the simplest types of problems because the events are independent. So: On your first draw, there is a 10/23. That probability remains the same for each draw because you are always replacing the marble. Next, you can imagine this as a chain of events. Chances on the first draw are 10/23. On the second draw, it will be 10/23 x 10/23, and for the third draw, 10/23 x 10/23 x 10/23. Or (10/23)^3 Quote Link to comment Share on other sites More sharing options...
Monica_in_Switzerland Posted January 3, 2017 Share Posted January 3, 2017 Often times, you would daw a probability tree to get a better idea of what is happening. Here's how the tree would start, but I didn't type out all of the third column because the formatting would take forever. :-) In bold is the desired outcome. You multiply the odds of each event occurring as you go across to get your final probability for the chain of three events. 1st draw 2nd draw 3rd draw yellow (etc) yellow green blue yellow green green green blue yellow blue green blue 1 Quote Link to comment Share on other sites More sharing options...
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