camitava wrote:
Need clarification on SET questions
I need some clarification on the set questions.
I see two formulas and little confused about when to use which one.
1) AUBUC = A + B + C - {A n B + B n C + C n A} + A n B n C
2) Total = A + B + C - {A n B + B n C + C n A} - 2* A n B n C
Can some one give example of each and also tell what is different?
Stmt - 1: AUBUC means all of A, B and C with the common data coming only for one time. I think I am not being able to make u clear! Say,
A = {x,y,z,a,b,c}
B = {z,x,r}
C = {a,b,p}
AUBUC = {x,y,z,a,b,c,r,p}
Now
Stmt - 2: Now here by the word
TOTAL, it represents -
TOTAL = {x,y,z,a,b,c,,z,x,r,a,b,p}
Hope I am being able to make u clear!
While the explanation for the first formula is fine .. i dont think the second one is correct and more importantly the second formula it self does not seem to be correct and does not make any sense ..
@ igmat
Suppose you have a question that says there are 100 people and each one of them drinks tea, coffee or water .. then over here AuBuC = 100 that is AuBuC represents the group which had
atleast one of the above..that is when you use the first question ..
But suppose you have a question that says there are 100 people out of which 4 drink none ( tea, coffee, water).. then over here AuBuC = 100-4=96 ..
Consider a question
Of the 200 candidates who were interviewed for a position at a call center, 100 had a two-wheeler, 70 had a credit card and 140 had a mobile phone. 40 of them had both, a two-wheeler and a credit card, 30 had both, a credit card and a mobile phone and 60 had both, a two wheeler and mobile phone and 10 had all three. How many candidates had none of the three? ..
Over here A=100, B = 70, C= 140 AnB= 40, BnC= 30, AnC=60 and AnBnC= 10
Use the formula ..
A+B+C-(AnB+AnC+BnC)+AnBnC = AuBuC ( the ones who had atleat one of the three)
100+70+140-(40+30+60)+10 = 190 .. so that means 190 had atleast 1 of the 3 .. so the number of candidates who had none is 200-190 =10 ..
About the 2nd formula .. there seems to be something wrong with it. and as far as i can tell it means nothing ..
