If a mixture of ground meat consists of 2 pounds of veal...

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

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

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Cheers,
Brent