SOLUTION: A student is looking for history class and knows he must be in one of nine classrooms. Since the teacher does not allow students to enter after he has started class, and there is v

Question 1172696: A student is looking for history class and knows he must be in one of nine classrooms. Since the teacher does not allow students to enter after he has started class, and there is very little time left, the student decides to try randomly in only four classrooms.
a) In how many of the different choices of four classrooms are possible, the history class cannot be located?
b) What fraction of the possible choices will lead to "success"?
Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!



Hi  

The number of combinations of a set of n objects taken r at a time is given by nCr = .   

C(9,4) = 126  the number of the different choices of four classrooms possible

a) C(8,4) = 70 the number of choices the history class cannot be located

b) 126-70 = 56 choices right classroom could be be located

56/126 = 28/63 = 4/9  the fraction of the possible choices that will lead to "success".

Wish You the Best in your Studies.

 

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