# Math Help - Ideal waist size

1. ## Ideal waist size

Ok, everyone has been very helpful with my previous questions and helping me understand and work through the problems. Here is one that does not seem to have a linear equation behind it.

Ideal waist size.
According to Dr. Aaron R. Folsom of the University of Minnesota School of Public Health, your maximum ideal waist size is directly proportional to your hip size. For a woman with 40-inch hips, the maximum ideal waist size is 32 inches. What is the maximum ideal waist size for a woman with 35-inch hips?

2. Originally Posted by dkpeppard
Ok, everyone has been very helpful with my previous questions and helping me understand and work thought the problems. Here is one that does not seem to have a linear equation behind it.

Ideal waist size.
According to Dr. Aaron R. Folsom of the University of Minnesota School of Public Health, your maximum ideal waist size is directly proportional to your hip size. For a woman with 40-inch hips, the maximum ideal waist size is 32 inches. What is the maximum ideal waist size for a woman with 35-inch hips?
Directly proportional means that you have a relationship in the form of y=kx, where x and y would be hip size and waist size respectively. Plug in the given info to solve for k.

You could also do this by ratios. For a 40 in hip size, ideal waist size is 32 in. So the ratio of hip:waist is 40:32. This ratio is the same for any hip and waist size. So 35:x , where the hip size is 35 in and the ideal waist is x has the same ratio as 40:32.

$\frac{40}{32}=\frac{35}{x}$

Solve for x.

3. Originally Posted by Jameson
Directly proportional means that you have a relationship in the form of y=kx, where x and y would be hip size and waist size respectively. Plug in the given info to solve for k.

You could also do this by ratios. For a 40 in hip size, ideal waist size is 32 in. So the ratio of hip:waist is 40:32. This ratio is the same for any hip and waist size. So 35:x , where the hip size is 35 in and the ideal waist is x has the same ratio as 40:32.

$\frac{40}{32}=\frac{35}{x}$

Solve for x.
Ok, I see. Thank you. I will put this formula to work and solve for x. Once I have my answer I will post it back and see if you all concur.

Thank you again.

4. Originally Posted by Jameson
Directly proportional means that you have a relationship in the form of y=kx, where x and y would be hip size and waist size respectively. Plug in the given info to solve for k.

You could also do this by ratios. For a 40 in hip size, ideal waist size is 32 in. So the ratio of hip:waist is 40:32. This ratio is the same for any hip and waist size. So 35:x , where the hip size is 35 in and the ideal waist is x has the same ratio as 40:32.

$\frac{40}{32}=\frac{35}{x}$

Solve for x.
Ok, using my algebra tutoring software to help me, I have found x=28. Do you agree with this finding?

Therefore, $\frac{40}{32}=\frac{35}{28}$

5. Originally Posted by dkpeppard
Ok, using my algebra tutoring software to help me, I have found x=28. Do you agree with this finding?

Therefore, $\frac{40}{32}=\frac{35}{28}$
$x = \frac{32}{40} \cdot 35 = \frac{32}{8} \cdot 7 = 28$

You are correct

6. Originally Posted by e^(i*pi)
$x = \frac{32}{40} \cdot 35 = \frac{32}{8} \cdot 7 = 28$

You are correct
Many thanks!

7. Originally Posted by dkpeppard
Many thanks!
Jameson did all the hard work

8. Originally Posted by e^(i*pi)
Jameson did all the hard work
I thanked him too.