Question

Two friends are making lemonade to sell at their lemonade stand. First, they make 4 liters of lemonade containing 31% lemon juice, but that doesn't taste quite right to them. They decide to add some store-bought lemonade that is 26% lemon juice until they have a mixture that is 27% lemon juice. How much of the store-bought lemonade should they add?
Write your answer as a whole number or as a decimal rounded to the nearest tenth.

Answer 1

Let x be liters of 26% lemonade added.

(4·0.31 + x·0.26) / (4 + x) = 0.27
1.24 + 0.26x = 1.08 + 0.27x
0.16 = 0.01x
x = 16

They should add 16 liters of the store-bought lemonade.