SOLUTION: How many different ways can you score an 80 on a 10 question true- false quiz?

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Question 303837: How many different ways can you score an 80 on a 10 question true- false quiz?
Answer by graphmatics(170) About Me  (Show Source):
You can put this solution on YOUR website!
Well let us look at it as 10 questions worth 10 points each. To score 80, 8 questions must be correct. Lets look at each question being 10 points. For the first question there a 10 possible questions for the second if you observe clearly there are 9 next one their are 8, etc etc:. Let z be the number of possible 8 questions selected. Then:
z = 10+9+8+7+6+5+4+3
z = 52