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Algebra / Linear equations in two variables Difficulty: Easy

A chemist studying the impact of salt on a process mixes x kilograms of a low-salt mixture, which is 2 % salt by weight, with y kilograms of a high-salt mixture, which is 96 % salt by weight, to create 24 kilograms of a mixture that is 4 % salt by weight. Which equation represents this situation?

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Explanation

Choice B is correct. It’s given that a chemist mixes x kilograms of a low-salt mixture, which is 2% salt by weight. Multiplying 0.02 by the amount of the low-salt mixture, x kilograms, yields 0.02x kilograms of salt in the low-salt mixture. It's also given that the chemist mixes y kilograms of a high-salt mixture, which is 96% salt by weight. Multiplying 0.96 by the amount of the high-salt mixture, y kilograms, yields 0.96y kilograms of salt in the high-salt mixture. Therefore, the total amount of salt in the combined mixture is 0.02x+0.96y kilograms. It's given that the low-salt mixture and the high-salt mixture together create 24 kilograms of a combined mixture that is 4% salt by weight. Thus, the amount of salt in the combined mixture is 0.04(24) kilograms. Since the total amount of salt in the combined mixture equals the amount of salt in the low-salt mixture and the amount of salt in the high-salt mixture, the equation 0.02x+0.96y=(0.04)(24) represents this situation.

Choice A is incorrect. This equation represents a situation where the low-salt mixture is 96%, not 2%, salt by weight and the high-salt mixture is 2%, not 96%, salt by weight.

Choice C is incorrect. This equation represents a situation where the low-salt mixture is 96%, not 2%, salt by weight and the high-salt mixture is 2%, not 96%, salt by weight, and where the combined mixture contains 24 kilograms of salt, not 24 kilograms of a mixture that is 4% salt by weight.

Choice D is incorrect. This equation represents a situation where the combined mixture contains 24 kilograms of salt, not 24 kilograms of a mixture that is 4% salt by weight.