# If the instructions for cooking a turkey state "Roast turkey at 325 degrees for 20 minutes per pound," how many hours will it take to roast a 20-pound turkey at this temperature?

Apr 26, 2018

$6 \frac{2}{3}$ hours, or $6.66667$ hours

#### Explanation:

It takes 20 minutes for 1 pound of turkey to be cooked at 365 degrees:

$\left(\frac{20}{1}\right)$, where 20 is the number of minutes a pound needs to cook and 1 is one pound.

Create a proportion to solve for x, then cross-multiply.
$\left(\frac{20}{1}\right)$ = $\left(\frac{x}{20}\right)$

$\left(1 \cdot x\right)$ = $\left(1 x\right)$, or $x$

$20$$\cdot$$20$ = $400$

$x$ = $400$ minutes

Now that we have the minutes, we can solve for how many hours it would take. There are 60 minutes in an hour, which can be expressed as:

$\left(\frac{60}{1}\right)$, where 60 represents 60 minutes and 1 represents 1 hour. Create a proportion like the earlier step.

$\left(\frac{60}{1}\right)$ = $\left(\frac{400}{x}\right)$

$\left(60 \cdot x\right)$ = $60 x$
$\left(400 \cdot 1\right)$ = $400$

$400$ = $60 x$

Divide by 60 to isolate for x:

$\left(\frac{400}{60}\right)$ = $6 \frac{2}{3}$ hours, or $6.66667$ hours