Lesson 16Finding the Percentage
Learning Goal
Let’s find percentages in general.
Learning Targets
I can solve different problems like “60 is what percentage of 40?” by dividing and multiplying.
Lesson Terms
- percent
- percentage
Warm Up: True or False: Percentages
Problem 1
Is each statement true or false? Be prepared to explain your reasoning.
25% of 512 is equal to
. 90% of 133 is equal to
. 30% of 44 is equal to 3% of 440.
The percentage 21 is of 28 is equal to the percentage 30 is of 40.
Activity 1: Jumping Rope
Problem 1
A school held a jump-roping contest. Diego jumped rope for 20 minutes.
Jada jumped rope for 15 minutes. What percentage of Diego’s time is that?
Lin jumped rope for 24 minutes. What percentage of Diego’s time is that?
Noah jumped rope for 9 minutes. What percentage of Diego’s time is that?
Record your answers in this table. Write the quotients in the last column as decimals.
time (minutes)
percentage
time
Diego
Jada
Lin
Noah
What do you notice about the numbers in the last two columns of the table?
Activity 2: Restaurant Capacity
Problem 1
A restaurant has a sign by the front door that says, “Maximum occupancy: 75 people.” Answer each question and explain or show your reasoning.
What percentage of its capacity is 9 people?
What percentage of its capacity is 51 people?
What percentage of its capacity is 84 people?
Are you ready for more?
Problem 1
Water makes up about 71% of the Earth’s surface, while the other 29% consists of continents and islands. 96% of all the Earth’s water is contained within the oceans as salt water, while the remaining 4% is fresh water located in lakes, rivers, glaciers, and the polar ice caps.
If the total volume of water on Earth is 1,386 million cubic kilometers, what is the volume of salt water? What is the volume of fresh water?
Lesson Summary
What percentage of 90 kg is 36 kg? One way to solve this problem is to first find what percentage 1 kg is of 90, and then multiply by 36.
From the table we can see that 1 kg is
In general, to find what percentage a number
Suppose a school club has raised $88 for a project but needs a total of $160. What percentage of its goal has the club raised?
To find what percentage $88 is of $160, we find