Example

Solving a Punch Mixture Problem with a Known Total

Apply the seven-step problem-solving strategy to a mixture word problem involving a known total volume to find the amounts of two combined liquid ingredients.

Problem: Becca wants to mix fruit juice and soda to make a punch. She can buy fruit juice for $3 a gallon and soda for $4 a gallon. If she wants to make 2828 gallons of punch at a cost of $3.25 a gallon, how many gallons of fruit juice and how many gallons of soda should she buy?

  1. Read the problem: fruit juice (worth $3 per gallon) and soda (worth $4 per gallon). The total mixture is 2828 gallons at $3.25 per gallon.
  2. Identify what to find: the number of gallons of fruit juice and the number of gallons of soda.
  3. Name the unknowns using a single variable and the known-total technique. Let xx = the number of gallons of fruit juice. Then the number of gallons of soda is 28x28 - x. Organize in a table:
TypeGallonsPrice per gallon ($)Total Value ($)
Fruit juicexx333x3x
Soda28x28 - x444(28x)4(28 - x)
Punch28283.253.2528(3.25)=9128(3.25) = 91
  1. Translate into an equation. The value of the fruit juice plus the value of the soda equals the value of the punch: 3x+4(28x)=913x + 4(28 - x) = 91

  2. Solve the equation:

  • Distribute 44: 3x+1124x=913x + 112 - 4x = 91
  • Combine like terms: x+112=91-x + 112 = 91
  • Subtract 112112 from both sides: x=21-x = -21
  • Divide by 1-1: x=21x = 21 Find the number of gallons of soda: 2821=728 - 21 = 7.
  1. Check: 3(21)+4(7)=913(21) + 4(7) = 91 63+28=9163 + 28 = 91 91=9191 = 91

  2. Answer: Becca should buy 2121 gallons of fruit juice and 77 gallons of soda.

0

1

Updated 2026-05-02

Contributors are:

Who are from:

Tags

OpenStax

Intermediate Algebra @ OpenStax

Ch.2 Solving Linear Equations - Intermediate Algebra @ OpenStax

Algebra

Related