Cogito
Grade 6 Math · Chapter 2 · Lesson 2
Percent as a Rate per Hundred
A ratio with the second number fixed at 100.
10 problems · about 17 minutes · 6.RP.A.3
What this lesson teaches
The child understands percent as a rate per 100 and converts between percents, fractions, and decimals.
- A percent is a rate per hundred.
- 35% is 35/100 is 0.35.
- Fixing the second number at 100 makes percents comparable.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
2 problemsReview — Unit Rates: 84 miles in 2 hours. How many miles per hour?
Answer 42
Why 42 miles per hour.
Review — Comparing Two Ratios: Scale 4 : 7 so the first number is 12. What is the second?
Answer 21
Why 12 : 21.
Warm Up
Straightforward practice. Get the method working first.
4 problems17 out of 20 as a percent?
Answer 85
Why 85%.
What does "per cent" mean?
Answer Per hundred.
Why A percent is a rate per hundred.
7 out of 10 as a percent?
Answer 70
Why Scale by 10.
3 out of 4 as a percent?
Answer 75
Why Scale by 25.
Build It Up
The same ideas with more to keep track of.
2 problems12 out of 25 as a percent?
Answer 48
Why Scale by 4.
What is 0.6 as a percent?
Answer 60
Why 0.6 is 60 hundredths.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsThe Test: 45 out of 100 marks. What percent is that?
Answer 45 percent
Why 45%.
The Other Test: 9 out of 20 marks. What percent is that?
Answer 45 percent
Why 9 × 5 = 45, so 45%.