probablity

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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?

[gmatmachoman]

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

[selango]

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