Test Help!

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Giulie

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Sep 16, 2009
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I have a test this coming week and I am currently studying for it, however I've become stuck on a few problems. I worked them out but according to the teacher's answers I got them wrong. Unfortunately, the teacher does not go into further detail about how he got his answers. Please help! Thanks.

1. A college bookstore marks up the price it pays the publisher for a book by 20%. If the selling price of a book is $84 how much did the book store pay for the book?

2. A builder of tract homes reduced the price of a model by 15%. If the new price is $186,660 what was the original price?

3. Erik has $18,300 to invest and decides to put some in a CD that earns 2.5% interest per year and the rest in a low stock that earns 2.6%. How much did he invest in each to earn $468.85 interest in the first year?


Thanks!
 
Giulie said:
1. A college bookstore marks up the price it pays the publisher for a book by 20%. If the selling price of a book is $84 how much did the book store pay for the book?

Hint: book + 20% of book = 84

2. A builder of tract homes reduced the price of a model by 15%. If the new price is $186,660 what was the original price?

Hint: original price - 15% of original price = 186,660

3. Erik has $18,300 to invest and decides to put some in a CD that earns 2.5% interest per year and the rest in a low stock that earns 2.6%. How much did he invest in each to earn $468.85 interest in the first year?

Hint: x + y = 18300 ; .025x + .026y = 468.85
Click to expand...
 
Denis said:
Giulie said:
1. A college bookstore marks up the price it pays the publisher for a book by 20%. If the selling price of a book is $84 how much did the book store pay for the book?

Hint: book + 20% of book = 84

x + 0.2 * x = 84

1.2 * x = 84

x = 70

Now you show your work for the rest

2. A builder of tract homes reduced the price of a model by 15%. If the new price is $186,660 what was the original price?

Hint: original price - 15% of original price = 186,660

3. Erik has $18,300 to invest and decides to put some in a CD that earns 2.5% interest per year and the rest in a low stock that earns 2.6%. How much did he invest in each to earn $468.85 interest in the first year?

Hint: x + y = 18300 ; .025x + .026y = 468.85
Click to expand...
Click to expand...
 
Giulie said:
So for #2 its:

x-.15x=186,660

.85x-186,660

x=219,600
Click to expand...

You have the answers - so you know whether it is correct or not.
 
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