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15 votes
15 votes
Some please help me with this problem, I have tried it multiple times but still couldn't get the correct answer. :(

Some please help me with this problem, I have tried it multiple times but still couldn-example-1
User Finest
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2.8k points

1 Answer

11 votes
11 votes

These 2 events are dependent on each other, which means that the second event is based on what happened on Donna's first marble toss.

For starters, there are 2 blues out of 10, which means there is a 2/10 or 1/5 chance that Donna will draw a blue one.

The next time she tosses, 1 blue is left with only 9 marbles, since Donna already drew a blue one). That means there is a 1/9 chance that Donna will come out blue.

To get the combined odds, all she has to do is multiply 1/5 by 1/9, which gives her a 1/45 chance of drawing 2 blue marbles in a row.

User Felixmondelo
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