Question 970783
I am using the <a href="http://www.mathwords.com/c/combination_formula.htm">combination formula</a> n C r = (n!)/(r!*(n-r)!)


So for example, 7 C 4 = (7!)/(4!*(7-4)!) = (7!)/(4!*3!) = 5040/(24*6) = 35



There are 7+5+10 = 22 coins total



Number of ways to draw 4 dimes = 7 C 4 = 35
Number of ways to draw 3 nickels = 5 C 3 = 10
Number of ways to draw 1 quarter = 10 C 1 = 10


Number of ways to draw 4 dimes, 3 nickels, and 1 quarter = 35*10*10 = 3,500


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Number of ways to draw 8 coins = 22 C 8 = 319,770


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Summary:


Number of ways to draw 4 dimes, 3 nickels, and 1 quarter = 3,500


Number of ways to draw 8 coins = 319,770


Divide the two values: (3,500)/(319,770) = <font color="red">0.01094536698251</font> (this probability is approximate)