Answer:
22 pounds
Explanation:
The 1:2 mix of types A and B will cost ...
... $5.40 + 2×$4.30 = $14.00
for a 3-pound blend of coffee, one pound of which is type A.
There are $308/$14 = 22 such 3-pound blends, so 22 pounds of type A coffee.
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Comment on Strategy
For any mixture problem in which you are given specific ratios, it is convenient to consider a unit that has the components in those ratios. Here, the ratio is 1:2, so it is convenient to use a unit of 3 pounds. The number of units is the same as the number of pounds of A, so the problem is simply one of finding the number of units that have the required total price.
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You may see coin problems in which you have some relation between the quantities, for example twice as many nickels as dimes. The same strategy applies: consider a "unit" of 2 nickels and 1 dime, whose value is $0.20.
You can use this strategy even in cases where there are "5 more nickels than twice the number of dimes." You simply subtract the extra nickels from the total value and you're back to having an integer number of units of 2 nickels and 1 dime.