Lesson 7-6 for exercise sets. &KDSWHU Problem by the VariableRepresented FormulaPercent Proportion5 is what percent of 20? percent r• 20 5 205 100 n5 is 25% of what number? base 25% • b (^55) n 10025
What number is 25% of 20? percentage 25% • 20 p 20 n 10025
Of the bands in a festival, 40% are
performing for the first time. If 6 bands are
performing for the first time, how many
bands in all are performing?
Let nthe total number of bands that
are performing.
Solve:
600 40 n Cross multiply.
15 n
Check:
600 600 Tr u e
So 15 bands in all are performing.
Divide both sides
by 40 to isolate n.
40
100
(^6) ?
15
40 n
40
600
40
40
100
6
n
1 Chan spent an hour working on his essay.
He spent 24 minutes outlining and the rest
of the hour writing. What percent of an hour
did Chan spend writing?
Use the percent formula: r • b p
r • 60 24 Substitute 60 for band 24 for p.
r Divide by the GCF, 12.
40% time spent outlining
100% 40% 60% time spent writing
So Chan spent 60% of an hour writing.
40
100
2
5
2
5
24 12
60 12
Divide both sides by
60 to isolate r.
24
60
r• 60
60
2
Solve for b, the original number.
1.50% of bis 11.5. 2.37.5% of bis 48. 3.125% of bis 30.5.
Solve for the unknown percentage, base, or percent.
4.What percent of 25 is 30? 5.Find 250% of 250. 6.12 % of bis 0.4.
7.If 130% of a number is 26, is the number greater or less than 26?
If 50% of a number is 26, is the number greater or less than 26? Explain.
8.Discuss and Write Lamar’s survey of the seventh graders in his school
showed that 25% of them would like to be in a rock band. The rest
of the seventh graders, 54 students, said that they would notcare to
join a rock band. Explain how you would use this information to find
how many seventh graders there are in Lamar’s school.
1
2
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