algebra

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algebra

by mehrasa » Sat Nov 06, 2010 4:39 am
Abby, Brandon, Cedric, and Deirdre are planning to attend a concert. If their friend Kim also
goes with them, they will get a group discount on their tickets. If the total price of the tickets
with the group discount is the same as the total price of the tickets without the group discount,
how much is the discount?
A. 5%
B. 10%
C. 20%
D. 25%
E. 33%

is thr anyone help me i n this case. the answer is 'c' based on the answers given.
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by Rahul@gurome » Sat Nov 06, 2010 5:13 am
Let the original price of the ticket be $x. Let us look at the given answer choices one by one.
Price of 4 tickets = 4x
Price of 5 tickets = 5x

(A) 5x - 5% of 5x = 5x - (0.05)(5x) = 5x - 0.25x = 4.75x, which is not equal to 4x. So, this is not the correct option.
(B) 5x - 10% of 5x = 5x - (0.1)(5x) = 4.5x, which is again not equal to 4x. So, this is not the correct option.
(C) 5x - 20% of 5x = 5x - (0.2)(5x) = 4x, which is equal to 4x. So, this is the correct option.

[spoiler]The correct answer is (C).[/spoiler]
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by GMATGuruNY » Sat Nov 06, 2010 5:17 am
mehrasa wrote:Abby, Brandon, Cedric, and Deirdre are planning to attend a concert. If their friend Kim also
goes with them, they will get a group discount on their tickets. If the total price of the tickets
with the group discount is the same as the total price of the tickets without the group discount,
how much is the discount?
A. 5%
B. 10%
C. 20%
D. 25%
E. 33%

is thr anyone help me i n this case. the answer is 'c' based on the answers given.
When the answers are percentages and there is an unknown in the problem (in this case, the cost of the tickets), we can plug in our own number for the unknown.

Let original total cost = 100.
Without Kim, there are 4 people, so cost per ticket = 100/4 = 25.
With Kim, total cost without discount = 5*25 = 125.

Now look at the answer choices, which represent the discount. Which answer choice will reduce the cost to 100?

Answer choice C:
.2*125 = 25.
125-25 = 100. Success!

The correct answer is C.
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by mehrasa » Sat Nov 06, 2010 7:24 am
thnx Rahul and GMATGurue