Question 1155530
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When 9 marbles are drawn without replacement, there is one marble left.<br>
The probability that 3 red marbles are drawn -- i.e., that the remaining marble is green -- is 7/10; similarly, the probability that 2 red marbles are drawn is 3/10.<br>
The expected number of red marbles drawn is then<br>
{{{(7/10)*3+(3/10)*2 = 27/10 = 2.7}}}<br>