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i need help.
A price is discounted by 15%. Then, the price is discounted by 10%. the combination of these is _______
I Know _______ = 23.5% but have no idea how to explain/ do the problem on my own. HELP!
 Mar 27, 2014
 #1
avatar+33603 
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unknown:

:? i need help.
A price is discounted by 15%. Then, the price is discounted by 10%. the combination of these is _______
I Know _______ = 23.5% but have no idea how to explain/ do the problem on my own. HELP!




Let the original price be P.
Then the first discounted price is (1-0.15)*P = 0.85P
The 2nd discounted price is then (1-0.1)*0.85P = 0.765P
The overall discount as a fraction is therefore (P-0.765P)/P = 0.235
Expressed as a percentage this is 23.5%
 Mar 27, 2014
 #2
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thank you very much!
 Mar 27, 2014
 #3
avatar+128079 
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This isn't the most "mathematical" explanation.....but it might help anyway.

Let us suppose that something originally costs $100.

Now, let's suppose that we take 10% off. Well, looking at it another way, it must now just be "worth" 90% of what its original price was, i.e., $90.

Now, let's suppose that we take 15% off of that. Well, then the "new" price must just be 85% of the $90 (since we took 15% off), i.e., $76.50.

Well, the "final" price is just 76.5% of the original $100 price........thus we "took off" $23.50.....or 23.5% of 100 !!!

In terms of "math-speak," we could express this in the following way........100 - (100*.90*.85)......100 - (76.50)........Original Price - (Final Price) = "Discount"

This is simplistic, but I hope it helps you see it.......
 Mar 27, 2014

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