8-1 percent and estimation
DESCRIPTION
8-1 Percent and Estimation. Pages 334-337 Indicator(s) N8 Develop and analyze algorithms for computing with percents and demonstrate fluency in use. To estimate the percent of a number…. …you can use a fraction or a multiple of 10% or 1%. Example 1 Use a fraction to estimate 77% of 800. - PowerPoint PPT PresentationTRANSCRIPT
8-1 Percent and Estimation
Pages 334-337
Indicator(s) N8 Develop and analyze algorithms for computing with percents and demonstrate fluency in use.
To estimate the percent of a number…
…you can use a fraction or a multiple of 10% or 1%.
Example 1Use a fraction to estimate 77% of 800.
77% is about 75% or .
77% of 800 ≈ × 800
≈ 600So, 77% of 800 is about 600.
4
3
4
3
Example 2
Percents greater than 100. Estimate 137% of 50.137% is more than 100%,
so 137% is going to be greater than 50.
137% is about 140%.
140% of 50 = (100% × 50) + (40% × 50)
= (1 × 50) + ( × 50)
= 50 + 20 = 70
So, 137% of 50 is about 70.
Percents greater than 100
5
2
Example 3
Percents less than 1. Estimate 0.5% of 692.
0.5% is half of 1%.
692 is about 700
To find 1% of 700, change % to decimal and multiply.
1%= 0.01 SO… = 0.01 × 700
= 7
One half of 7 is 7 × or 3.5
So, 0.5% of 692 is about 3.5.
Percents less than 1
2
1
Example 4
Estimate 59% of 500.
10% of 500 is 50.
59% is about 60%.
60% of 500 is 6 × 10%.
6 × 50 = 300
So, 59% of 500 is about 300.
Estimate by using 10%
8-1 b
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