Percents of numbers: word problems
Key notes:
A percent is 1 part out of 100.
1% is equal to 1/100 or 0.01.
Proportions can be used to solve percent problems.
part / whole = percent / 100
Learn with an example
🔔 Sam ordered a set of beads. He received 90 beads, and 10% of them were green. How many green beads did Sam receive?
________ beads
Find 10% of 90.
The whole is 90.
The percent is 10%.
Let n represent the part.
Write a proportion to solve for n.
n / 90 = 10 / 100
100n = 10 · 90
100n = 900
100n ÷ 100 = 900 ÷ 100
n = 9
Sam received 9 green beads.
You could also find the answer by writing and solving an equation:
part = percentage of whole
n = 10% · 90
n = 0.1 · 90
n = 9
Sam received 9 green beads.
🔔 Luca’s town voted on a new speed limit. 60% of the 40 votes were in favour of the new speed limit. How many votes were in favour?
_____ votes
Find 60% of 40.
The whole is 40.
The percent is 60%.
Let n represent the part.
Write a proportion to solve for n.
n / 40 = 60 / 100
100n = 60 · 40
100n = 2,400
100n ÷ 100 = 2,400 ÷ 100
n = 24
24 votes were in favour of the new speed limit.
You could also find the answer by writing and solving an equation:
part = percentage of whole
n = 60% · 40
n = 0.6 · 40
n = 24
24 votes were in favour of the new speed limit.
🔔 The students in Ernest’s grade voted to select a guest speaker. 30% of the students voted for a famous athlete. If there are 100 students in Ernest’s grade, how many students voted for the athlete?
_______ students
Find 30% of 100.
The whole is 100.
The percent is 30%.
Let n represent the part.
Write a proportion to solve for n.
n / 100 = 30 / 100
100n = 30 · 100
100n = 3,000
100n ÷ 100 = 3,000 ÷ 100
n = 30
30 students voted for the famous athlete.
You could also find the answer by writing and solving an equation:
part = percentage of whole
n = 30% · 100
n = 0.3 · 100
n = 30
30 students voted for the famous athlete.
Let’s practice! 🖊️
