OG : DS : 79

statement 2 is INSUFFICIENT because we can't compare the costs

cost of the computer in the state A:

C1 = P1 $ - (t1 %)*(P1 $) = P1 $(1 - t1 %)

cost of the computer in the state B:

C2 = P2 $ - (t2 %)*(P2 $) = P2 $(1 - t2 %)

2- P1.t1 > P2.t2

C1 > C2 ?

P1 $(1 - t1 %) > P2 $(1 - t2 %) ?

we need more information about prices

hope it helps!

Best,
Maciek

suppose p1=100 t1=10% so total cost = 100-10=90

p2=100 t2=5% so cost=100-5=95

1. t1>t2 but it doesnt tell about p1 n p2 so not suff

2.p1.t1>p2.t2 this also nt suff

combing we dont nething soE

I have a solution which differs from the Official Guide answer - E. I think the question's answer is C, i.e. both statements together are sufficient to answer the question.

Question is if P1 + T1/100 (P1) > P2 + T2/100 (P2) ??

Solution:

From Statement 1 : T1 > T2
So, T1/100 > T2/100

So, 1 + T1/100 > 1 + T2/100

So, P1 (1 + T1/100) > P1 (1 + T2/100) -------------- I

From Statement 2 : P1T1 > P2T2

Dividing Statement 2 by Statement 1, we have

P1T1/T1 > P2T2/T2

So, P1 > P2 ------------------------------------------------ II

From Statement I and II,

P1 (1 + T1/100) > P2 (1 + T2/100)

Thus, P1 + T1/100 (P1) > P2 + T2/100 (P2)

Shouldn't the answer be C?

Please correct me if I am wrong guys??

All4GMAT wrote:From Statement 1 : T1 > T2

From Statement 2 : P1T1 > P2T2

Dividing Statement 2 by Statement 1, we have

P1T1/T1 > P2T2/T2
Please correct me if I am wrong guys??

This is your mistake, All4GMAT !!

You CANNOT divide inequalities!

Example: 2 > 1 and 5 > 2 but 2/5 > 1/2 is wrong...


Another important thing: the difference between your "mathematization" of the question stem and the others: you think that the tax is put OVER the price, the others believe the price INCLUDES the tax.... I guess it´s a matter of the country you live on, because here in Brazil "your" approach would be more natural, but I BELIEVE that in USA it is the other way round, therefore I guess you should use Maciek´s structure (very well explained!) for the GMAT, but it seems to me that the question itself relates to the TOTAL COST and therefore, it seems to me, that this concept should be translated by "P1 > P2 ?"

nasir wrote:Leo can buy a certain computer for P1 $ in state A, where the sales tax is t1 %, or he can buy the same computer for P2 $ in state B, where the sales tax is t2 %. is the total cost of the computer greater in state A than in state B ?

1- t1 > t2

2- P1.t1 > P2.t2

I suggest the following solution:

pre-tax amount in state A = p1 (1 - t1/100)
pre-tax amount in state B = p2 (1 - t2/100)

--------------------------------------------
Focus in the question: p1 > p2 ?
--------------------------------------------

(1) BIFURCATES (therefore is insufficient):

> Take t1 = 20, t2 = 10 and p1 = p2 = 100, that answers in the negative ;
> Take t1 = 20, t2 = 10 and p1 = 100, p2 = 90, that answers in the positive ;


(2) BIFURCATES (therefore insufficient):

> Take p1 = 100 , t1 = 20 (p1.t1 = 2,000) and p2 = 90 , t2 = 15 (p2.t2 = 900+450 = 1,350) answering in the positive;
> Take p1 = 80 , t1 = 20 (p1.t1 = 1,600) and p2 = 90 , t2 = 15 (p2.t2 = 900+450 = 1,350) answering in the negative;


(1+2) BIFURCATES (insufficient, therefore answer is E):

Same examples as in (2) , because there (in both cases) I used t1 > t2 as sttm (1) asks/restricts!!

Regards,
Fabio.