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!

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 ..

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 ..

Gabriel, thanks for rectifying me! Ha ha ha! U know one thing that I made a wild guess about the second stmt what igmat has mentioned in his post. I thought may be this is something what igmat wants to say. So I made a wild guess. But I had a doubt whether I am going to direct it in some wrong way or not. Thanks once again, Gabriel for rectifying me! 8)

Hi Everyone,

Just wanted to close the loop for the question that I originally posed.

Based on the many answers that I got on the post as well as my personal verification, only formula 1 makes sense.

I found the second formula in MILC gmat manual and I am not sure what it meant. So as suggested by many others, stick to formula 1.

Thanks.