Answer:
The largest advertisement she can afford has dimensions of 5 in x 10/3 in
Step-by-step explanation:
Assume the dimensions of the advertisement are L and W.
The area of the advertisement is:
A = L.W
The ratio length/width is 3:2, thus the proportion is:
[tex]\displaystyle \frac{L}{W}=\frac{3}{2}[/tex]
Thus:
[tex]\displaystyle L=\frac{3}{2}W[/tex]
The area is:
[tex]\displaystyle A=\frac{3}{2}W^2[/tex]
Since the square inch of advertisement space sells for $3, the cost for Anna to purchase it is:
[tex]\displaystyle C=3\cdot\frac{3}{2}W^2[/tex]
Simplifying:
[tex]\displaystyle C=\frac{9}{2}W^2[/tex]
This cost can be a maximum of $50, thus:
[tex]\displaystyle \frac{9}{2}W^2=50[/tex]
Multiplying by 2:
[tex]9W^2=100[/tex]
Solving for W:
[tex]\displaystyle W=\sqrt{\frac{100}{9}}=\frac{10}{3}[/tex]
[tex]\displaystyle W=\frac{10}{3}[/tex]
And
[tex]\displaystyle L=\frac{3}{2}\cdot \frac{10}{3}[/tex]
L = 5
Thus the largest advertisement she can afford has dimensions of 5 in x 10/3 in
