LUANDATO wrote:A mixture of ground meat consists of 2 pounds of veal that costs x dollars per pound, and 5 pounds of beef that costs y dollars per pound. What is the cost of the mixture in dollars per pound?

$$A.\ 2x\ +\ 5y$$
$$B.\ \frac{2x+5y}{xy}$$
$$C.\ 5\left(2x+5y\right)$$
$$D.\ x+y$$
$$E.\ \frac{2x+5y}{7}$$

We can use the WEIGHTED AVERAGE formula:
Weighted average of groups combined = (group A proportion)(group A average) + (group B proportion)(group B average) + (group C proportion)(group C average) + ...

When we COMBINE the meats, the TOTAL weight = 2 + 5 = 7 pounds.
So, veal comprises 2/7 of the TOTAL mixture
Beef comprises 5/7 of the TOTAL mixture

Plug values into formula:

Weighted average of groups combined = (2/7)(x) + (5/7)(y)
= 2x/7 + 5y/7
= (2x + 5y)/7

Answer: E

---------------------------------------

For more information on weighted averages, you can watch this free GMAT Prep Now video: https://www.gmatprepnow.com/module/gmat- ... ics?id=805

Here are some additional practice questions related to weighted averages:
- https://www.beatthegmat.com/weighted-av ... 17237.html
- https://www.beatthegmat.com/weighted-av ... 14506.html
- https://www.beatthegmat.com/average-wei ... 57853.html
- https://www.beatthegmat.com/averages-qu ... 87118.html

Cheers,
Brent