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Originally Posted by dadaruh
Hey, since I recognized the answer you have given to Lego's similar question, i got the way you answered to #3. However, regarding the question, I thought that none-blue can be found if we dare to find the all-of-them-blues and subtract from 1. It seems wrong approach but, could you give a reason?
i appriciate.
ugur
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You could have also used the 1-Blue approach, although as twin said, its long.
I think you missed on one of the possible outcomes.
We have 2 BLUE or 1 BLUE
in the case of two blue, its simply
2/8 * 1/7 = 1/28
In the second case, one blue and one not, you must have considered:
2/8*6/7 = 6/28.
But you didnt consider it the other way around, where the FIRST is not blue and the second is blue,
6/8 * 2/7 = 6/28
so adding them up, we get 13/28
So 1- 13/28 = 15/28
Hope that helps.......