Answer:
126
Step-by-step explanation:
To calculate this, we need to assume at least one white marble will be picked... so let's take it out of the bag. Then we need to pick 4 more marbles... it's just then a combination calculation.
How many marbles is there in total? 4 + 3 + 2 + 1 = 10
We do just as if we had removed one white marble from the bag... so that leaves 9 in the bag.
We have to pick 4 out of those 9.... so, it's simple combination calculation:
C(9,4) = 9! / (4! (9--4)!) = 9! / (4! 5!) = 126
Some of those grabs will have 2 white marbles... but we're assured that there are 126 ways to combine the 10 marbles so there's at least one white in the 5 picked (since we forced it in our calculations).
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