khushbumodi wrote:
pushpitkc wrote:
Formula used
P(Total) = P(A) + P(B) + P(C) - P(exactly 2) - 2*P(all 3)
Substituting values
85 = 50 + 30 + 20 - P(exactly 2) - 2*5
P(exactly 2) = 90 - 85 = 5
Percentage or people who liked more than one product = p(exactly 2) + p(all 3) = 5+5 = 10(Option B)
Sorry but I am a bit confused here!
In the formula that you used, isn't that supposed to ADD and not subtract the number for All Three?
You subtracted twice that number instead of adding it once. Can you please explain how did you come up with that formula?
Thanks
Sent from my SM-N9200 using
GMAT Club Forum mobile appP(Total) = P(A) + P(B) + P(C) - P(exactly 2) - 2*P(all 3) is the formula whose clarification you had asked for
The clarification is as follows :
P(A) = P(Only A) + P(A U B) + P(A U C) + P(A U B U C)
P(B) = P(Only B) + P(B U C) + P(B U A) + P(A U B U C)
P(C) = P(Only C) + P(C U A) + P(C U B) + P(A U B U C)
P(exactly 2) = P(A U B) + P(A U C) + P(B U C)
P(all 3) = P(A U B U C)
Substituting these values in the formula,
P(Total) = P(A) + P(B) + P(C) - P(exactly 2) - 2*P(all 3)
P(Total) = P(Only A) +
P(A U B) + P(A U C) + P(A U B U C) + P(Only B) +
P(B U C) + P(B U A) +
P(A U B U C) + P(Only C) + P(C U A) + P(C U B) + P(A U B U C) -
P(A U B) - P(A U C) - P(B U C) - 2* P(A U B U C) P(Total) = P(Only A) + P(Only B) + P(Only C) + P(B U A) + P(C U A) + P(C U B) + P(A U B U C)
_________________
You've got what it takes, but it will take everything you've got