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  1. Ellie is dropping marbles into a box one at a time in the following order: red, white, white, blue, blue, blue: red, white, white, blue, blue, blue: ... How many marbles will be in the box right after the 100th blue one is put in?

so i've noticed that every in one sequence there will be 3 blue, 2 white, and one red. given that.

I'm stuck on how to get 202 as the answer. What's the next step to solve this problem?

1 Answers1

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Hint. Ellie will have to put three blue marbles in the box, $33$ times. How many marbles are now in the box?

But then she has to put one more blue in. She can't do this immediately as she has to put certain numbers of red and white marbles in first. So. . . ?

David
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  • 198 marbles now. I didn't ask the question "She can't do this immediately as she will have to put certain numbers of red and white marbles in as well. So. . . ?" when solving the problem. After the 99th marble, she must add 1 one red, 2 white b4 she adds the 100th marble. Why didn't I ask that question? –  Sep 01 '14 at 01:49
  • 202 total after the 100th blue marb. –  Sep 01 '14 at 01:50