Question

Celine has a bottle that contains 20% milk and the rest water. The bottle has 1 liter of water. Part A: Write an equation using one variable that can be used to find the total number of liters of milk and water in the bottle. Define the variable used in the equation and solve the equation. Hint: 0.2x represents the number of liters of milk in the bottle. (5 points) Part B: How many liters of milk are present in the bottle? Show your work. (5 points)

Answer 1

A) 0.2x +1 = x . . . . x is the volume of liquid in the bottle (liters)

B) 0.25 liters of milk are in the bottle

Explanation:

It is often convenient to define a variable as the answer to the question. Here, the question says "find the total number of liters of milk and water in the bottle", so that is the definition of our variable, x.

A) The problem statement tells us that 20% of the liquid is milk, so that amount is 0.2x (as the hint says). Then the sum of milk volume and water volume is the total volume:

0.2x + 1 = x . . . . . . . an equation in one variable that can find total volume

We can solve this equation by subtracting 0.2x, then dividing by the coefficient of x.

1 = 0.8x

1/0.8 = x = 1.25 . . . the total number of liters of milk and water is 1.25

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B) The number of liters of milk is 0.2x, so is 0.2·1.25 = 0.25

There are 0.25 liters of milk in the bottle.