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 storeâ€™s revenues from newspaper sales was from Newspaper A and if p percent of the newspapers that the store sold were copies of newspaper B, which of the following expresses r in terms of p?
A. 100p / (125 â€“ p)
B. 150p / (250 â€“ p)
C. 300p / (375 â€“ p)
D. 400p / (500 â€“ p)
E. 500p / (625 â€“ p)
I am assuming you meant newspaper B
No the question is correct. We need to consider revenues
and the # of copies
Let a = # of newpapers sold for type A
Let b = # of newpapers sold for type B
So equation for revenues
: r = [a.1/(a.1+b.125)]*100 ---(I)
So equation for # of copies
: p = [a/(a+b)]*100 ---(II)
Eliminate b/a from both the equations.
From (I) (a+1.25b)/a = 100/r ==> b/a = 0.8*(100 - r)/r ------(III)
From (II) b/a = (100 - p)/p ---(IV)
Combine (III) and (IV). We get 0.8*(100 - r )/r = (100 - p)/p.
Simplify and we get r = 400p / (500 â€“ p). So answer is D
Does this make sense?