Question 857043
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Hi,
first of all 25 Questions(assuming each counts 4 pts) 
therefore: 20 or more correct would result in 80 points or higher.
Will get You started...
P(100) = (1/3)^22(1/2)^3   all right 
P(96) = {{{(1/3)^22(1/2)^3  +  22C21(1/3)^2(2/3)^1( 3C1(1/2)^1(1/2)^2)}}} one wrong
the more ways it can happen .. the longer the string gets...final addition will have similar multiples...helps some
92 = {{{(1/3)^22(1/8) + 22C21(1/3)^21(2/3)^1(3/8) +  22C20(1/3)^20(2/3)^2(3/8)}}} 2 wrong Note: 3C1 = 3C2 = 3
88
84
80