Problem:

Last Sunday a certain store sold copies of Newspaper A for $1.00 each and copies of Newspaper B for $1.25 each, and the store sold no other newspapers that day.

If r percent of the store's revenues from newspapers sales was from Newspaper A and if p percent of the newspapers that the store sold were copies of newspaper A, which of the following expressies r in terms of p?

100p/125-p 150p/250-p 300p/375-p
400p/500-p 500p/625-p

Being a business major, I understand revenue, profit, and cost percentages... but this one.

Formal answer:

If percent of the copies sold were A (A = p), then (100-p) percent were B. The ratio of the prices of A and B are in a 4:5 ratio, so the ratio of the revenue generated by A to that generated by B is 4p: 5(100-p) OR 4p/(500-5p). The ratio of the revenue generated by A to the total revenue is 4p/ (4p + 500 - 5p) or 4p/500-p. I'm alright up to this point.

The next part of the final answer states... "Thus, A's revenue is 400p/(500-p)percent" This does not make sense to me. Why multiply the 4 by 100- answer was already in a percentage format?

[kevin]

Originally Posted by wvspidermonkey

Problem:

Last Sunday a certain store sold copies of Newspaper A for $1.00 each and copies of Newspaper B for $1.25 each, and the store sold no other newspapers that day.

If r percent of the store's revenues from newspapers sales was from Newspaper A and if p percent of the newspapers that the store sold were copies of newspaper A, which of the following expressies r in terms of p?

100p/125-p 150p/250-p 300p/375-p
400p/500-p 500p/625-p

Being a business major, I understand revenue, profit, and cost percentages... but this one.

Formal answer:

If percent of the copies sold were A (A = p), then (100-p) percent were B. The ratio of the prices of A and B are in a 4:5 ratio, so the ratio of the revenue generated by A to that generated by B is 4p: 5(100-p) OR 4p/(500-5p). The ratio of the revenue generated by A to the total revenue is 4p/ (4p + 500 - 5p) or 4p/500-p. I'm alright up to this point.

The next part of the final answer states... "Thus, A's revenue is 400p/(500-p)percent" This does not make sense to me. Why multiply the 4 by 100- answer was already in a percentage format?

If the ratio the number of gumdrops to the total number of sweets is 3 to 4, what percent of the sweets are gumdrops? 300/4= 75%

We know that r%=r/100=4p/(500-p), solve for r