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probablity

by [email protected] » Wed Jun 30, 2010 9:11 pm
A group of 50 students were required to clear 2 tasks, one in rock-climbing and the other in bridge crossing during an adventure sports expedition. 30 students cleared both the tasks. 37 cleared bridge crossing, 38 students cleared rockclimbing. How many students could not clear any task?
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by gmatmachoman » Wed Jun 30, 2010 9:24 pm
[email protected] wrote:A group of 50 students were required to clear 2 tasks, one in rock-climbing and the other in bridge crossing during an adventure sports expedition. 30 students cleared both the tasks. 37 cleared bridge crossing, 38 students cleared rockclimbing. How many students could not clear any task?
P(AUB)= P(A) +P(B) -P(AnB)



= 37+38-30
=45

Total= P(AUB) + Neither of the both

50 = 45+X



X=5
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by selango » Wed Jun 30, 2010 9:25 pm
Total=50

P(RnB)=30

P(R)=38

P(B)=37

Total=P(R)+P(B)-P(RnB)+neither

50=38+37-30+neither

neither = 5
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