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Re: If an item that originally sold for z dollars was marked up [#permalink]
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Assume Z=100, x=10, y=10. So final price is 99. Now put these value each option. Only option A will give right answer.
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Re: If an item that originally sold for z dollars was marked up [#permalink]
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Ans is A

x% rise and y percent fall
net change formula is (a + b + ab/100 )% if rise +ve and if fall -ve
so x is + and y is -
net change will be x-y - xy/100
and this is % of z
so net change ie rise => z( x-y-xy/100)1/100
and last price was z
so new one is z+ z( x-y - xy/100)1/100
so becomes A
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Re: If an item that originally sold for z dollars was marked up [#permalink]
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GMATT73 wrote:
If an item that originally sold for z dollars was marked up by x percent and then discounted by y percent, which of the following expressions represents the final price of the item?

A. (10,000z + 100z(x – y) – xyz)/10,000

B. (10,000z + 100z(y – x) – xyz)/10,000

C. (100z(x – y) – xyz)/10000

D. (100z(y – x) – xyz)/10000

E. 10000 /(x – y)


Let z=1, x=0 and y=100.
Since the final discount = 100%, the final price = 0.

Now plug z=1, x=0 and y=100 into the five numerators to see which yields a final price of 0.
Since xyz = 0, this term can be ignored.
Only the numerator in A yields a value of 0:
10,000z + 100z(x-y) = 10,000*1 + 100*1*(0-100) = 10,000 - 10,000 = 0.

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Re: PS XYZ [#permalink]
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GMATT73 wrote:
If an item that originally sold for z dollars was marked up by x percent and then discounted by y percent, which of the following expressions represents the final price of the item?

(A) [10,000z + 100z(x – y) – xyz]/10,000
(B) [10,000z + 100z(y – x) – xyz]/10,000
(C) [100z(x – y) – xyz]/10,000
(D) [100z(y – x) – xyz]/10,000
(E) 10,000/(100yz + xy)

Actually figured it out as I was typing it in by picking the following numbers:

z=$10, x=20%, y=50% 1.2z*.5= 6

Final price should be $6.

Any other ways?


If mark-up is x%, new price will be (100+x)/100 times old price.

Discounted by y% means new price will be (100-y)/100 times old price.

So we have final price =z(100+x)(100-y)/10000
and the terms rearranged give A. :)
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To me, for some questions, picking nos. and applying those in each ans choice and finding the right choice seems tedious. I guess it depends on the method of practice and the strength of the individual, as I see in many threads, and of course, the time pressure.
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Re: If an item that originally sold for z dollars was marked up [#permalink]
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GMATT73 wrote:
If an item that originally sold for z dollars was marked up by x percent and then discounted by y percent, which of the following expressions represents the final price of the item?

A. (10,000z + 100z(x – y) – xyz)/10,000

B. (10,000z + 100z(y – x) – xyz)/10,000

C. (100z(x – y) – xyz)/10000

D. (100z(y – x) – xyz)/10000

E. 10000 /(x – y)


We are given that an item that originally sold for z dollars was marked up by x percent and then discounted by y percent; thus, the final price of the item is:

z(1 + x/100)(1 - y/100)

z[(100 + x)/100][(100 - y)/100]

z[(10,000 + 100x - 100y - xy)/10,000

[(10,000z + 100xz - 100yz - xyz)/10,000

[(10,000z + 100z(x - y) - xyz)/10,000

Answer: A
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Re: PS XYZ [#permalink]
GMATT73 wrote:
If an item that originally sold for z dollars was marked up by x percent and then discounted by y percent, which of the following expressions represents the final price of the item?

(A) [10,000z + 100z(x – y) – xyz]/10,000
(B) [10,000z + 100z(y – x) – xyz]/10,000
(C) [100z(x – y) – xyz]/10,000
(D) [100z(y – x) – xyz]/10,000
(E) 10,000/(100yz + xy)

Actually figured it out as I was typing it in by picking the following numbers:

z=$10, x=20%, y=50% 1.2z*.5= 6

Final price should be $6.

Any other ways?


Matt, that is the easier way. Other way is to directly multiply and take the common factors out..but that seems to be time taking in this problem. As you know, whenever its possible, solving by substituting the numbers is the best way to solve problems when we are under time pressure :wink:
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Re: If an item that originally sold for z dollars was marked up [#permalink]
Use the rule for consecutive percentage changes. If there are consecutive %changes a and b. Then a+b+(ab/100) % is the net change. Substitute for x and y and solve. The answer is option A.
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Re: If an item that originally sold for z dollars was marked up [#permalink]
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Re: If an item that originally sold for z dollars was marked up [#permalink]
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