Question

practice using estimation with decimals
study the example showing how to estimate a difference using decimal grids. then solve problems 1–4.
example
kamala has 2.73 liters of lemonade. she wants to have about 5.5 liters for her party. about how much more lemonade does kamala need?
one way to estimate is to round to the nearest tenth. 5.5 is given to the nearest tenth. 2.73 is about 2.7.
image of decimal grids with labels -2 and -0.7
kamala needs about 2.8 liters more of lemonade.

1. look at the example. does this situation require an exact answer, or is the estimate enough? explain.
2. suppose kamala wants to have exactly 5.5 liters of lemonade for her party. how much more lemonade does she need? show your work.

Explanation:

Step1: Identify the operation

We need to find the difference between the desired amount (5.5 liters) and the current amount (2.73 liters). The formula for the amount needed is $ \text{Amount Needed} = \text{Desired Amount} - \text{Current Amount} $.

Step2: Substitute the values

Substitute the given values into the formula: $ 5.5 - 2.73 $.

Step3: Perform the subtraction

To subtract decimals, we align the decimal points:

$$\begin{align*} 5.50 - 2.73 &= (5 + 0.50) - (2 + 0.73) \\ &= (5 - 2) + (0.50 - 0.73) \\ &= 3 + (-0.23) \\ &= 2.77 \end{align*}$$

Answer:

2.77 liters