GMAT Word Problems: If the grocer buys another 100 pounds…

A grocer has 400 pounds of coffee in stock, 20 percent of which is decaffeinated. If the grocer buys another 100 pounds of coffee of which 60 percent is decaffeinated, what percent, by weight, of the grocer's stock of coffee is decaffeinated?

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Explanation	Calculations	Help
$We translate "20 percent" and "of 400" into an equation to find the decaffeinated weight in the initial stock.$	$D_{1} = \frac{20}{100} \times 400 = 80$
$We translate "60 percent" and "of 100" into an equation to find the decaffeinated weight in the additional purchase.$	$D_{2} = \frac{60}{100} \times 100 = 60$
$We add the two decaffeinated weights.$	$D = D_{1} + D_{2} = 80 + 60 = 140$
$We add the initial and additional coffee weights.$	$T = 400 + 100 = 500$
$We divide the total decaffeinated weight by the total weight and multiply by 100 to find the percent decaffeinated.$	$P = \frac{D}{T} \times 100 = \frac{140}{500} \times 100 = 28%$

28 % (A)

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