One Hundred Percent


Show Percentages by Completing Double Number Line Diagrams.

Complete the double number line diagram to show the percentages that correspond to the original amount and to the new amount.

(1). The gas tank in dad’s car holds 12 gallons. The gas tank in mom’s truck holds 50% more than that.

(2). At a movie theater, the size of popcorn bags decreased 20%. The old bags held 15 cups of popcorn.

(3). A school had 1,200 students last year and only 1,080 students this year. 

(4). One week gas was $1.25 per gallon. The next week gas was $1.50 per gallon. 

(5). After a 25% discount, the price of a T-shirt was $12.

(6). Compared to last year, the population of Boom Town has increased 25%.The population is now 6,600.


Use Double Number Line to Solve Percentage Problems.

A juice box has 20% more juice in its new packaging. The original packaging held 12 fluid ounces. How much juice does the new packaging hold? Two students; Priya and Clare both attempt to solve the problem.

(1). Do you agree with either of them? Explain your reasoning.
(2). Clare’s diagram could represent a percent decrease. Describe a situation that could be represented with Clare’s diagram.


Understanding Percentage Problems.

Noah thinks the answers to these two questions will be the same.

  • This year, a herd of bison had a 10% increase in population. If there were 550 bison in the herd last year, how many are in the herd this year?
  • This year, another herd of bison had a 10% decrease in population. If there are 550 bison in the herd this year, how many bison were there last year?

Do you agree with him? Explain your reasoning.


A bakery used 25% more butter this month than last month. If the bakery used 240 kilograms of butter last month.


Last week, the price of oranges at the farmer’s market was $1.75 per pound. This week, the price has decreased by 20%.


The equation d = 3 represents the relationship between the distance (d ) in inches that a snail is from a certain rock and the time (t ) in minutes.