Question 1173324
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Here is a quick and easy way to solve 2-part "mixture" problems like this without formal algebra (if, of course, a formal algebraic solution is not required).<br>
The price of the mixture per kilogram, P500, is 1/3 of the way from P450 to P600, the prices per kg of the two ingredients.  (look at it as 500 begin 1/3 of the way from 450 to 600 on a number line....)<br>
That means 1/3 of the mixture is the more expensive ingredient.<br>
That means the 10kg of the less expensive chocolate is 2/3 of the mixture; and that mean 1/3 of the mixture is 5kg.<br>
ANSWER: 5kg<br>
CHECK:
10(450)+5(600) = 4500+3000 = 7500
15(500) = 7500<br>