Chapter 3 Review

Chapter 3 Review Best Be Taking Notes: This is what your test is on. By: Ms. Dewey-Hoffman

Section 3.1: Rounding and Estimating
What is rounding?
Rounding: taking a number and making it more manageable to a certain placeholder.
Do this when you do not need an exact value.
What is estimating?
Rounding and finding the product, quotient, sum, or difference is estimating.
This helps find an appropriate answer that is not exact. But close to the real answer.

Three Ways of Estimating “about” or “approximately equal to”
Rounding:
Round to different placeholders.
Estimating:
Round to the same placeholder.
Front-End Estimating:
Often closer to the exact answer then by rounding!
Add the left-side of the decimal, then round and add the right-side of the decimal. Finally: add the two sides.
Clustering:
When values are close to one value, make them all the same value and add.

Example Problems: Round to the Underlined Place Value.
58.6 5 9
3 2 .876
.87 3 24
.00 6 49

Example Problems: Estimate by Rounding
$37.99 + $32.06  ______
0.379 + .899  ______
72.98 – 28.301  ______

Example Problems: Use Front-End Estimation
10.95 + 11.75 + 23.23  ______
$15.24 + $0.55 + $9.99  _______
5.32 + 3.12 + 7.34  _______

Example Problems: Estimate by Clustering
13.45 + 12.95 + 14.02  ________
9.5 + 9.25 + 9.85  ________
$99.56 + $100.25 + $101.04  _______

Word Problem
Lake Superior, the largest of the Great lakes, has an area of 31,760 miles ². Lake Erie, the smallest of the Great Lakes, has an area of 9,920 miles ². About how much larger is Lake Superior than Lake Erie?
How would you solve this problem?
What does “ABOUT” mean here?

Section 3.2: Estimating Decimal Products and Quotients
Estimating the products and quotients of decimals is a good way of checking mental math.
Multiplying Decimals: Estimate using any method.
Dividing Decimals: Round the Divisor, Round the Dividend (to a compatible number), then Divide!

Example Problems: Multiplication Estimation
32.57 • 4.2  _______
193.7 • 1.78  _______
16.33 • 3.5  _______

Example Problems: Division Estimation
7.95  2.1  ______
120.32  4.948  ______
$32.42  4.68  ______

Word Problem: Estimation
Shari is planning a 450 miles car trip. Her car can travel about 39 miles on a gallon of gasoline. Gasoline costs $1.19/gal. About how much will the gas cost for her trip?
450 miles   40 miles/gallon  11 gallons
11 gallons • $1.19/gallon  $12 on gas.

Section 2.3: The 3 Ms.
Measures of Central Tendency
Mean ? Data items divided by number of data items.
Median ? The middle data item when data items are in order. Or the average of the two middle most data items.
Mode ? The date item that occurs most often. There can be 1 mode, no mode, or multiple modes.
Outlier ? A data value that is much lower or much higher then the other data items.

Example Problems: Find Me M, M & M for all 3. Outlier?
14.5, 7, 13.5, 15, 15, 16, 13.5
53, 53, 55, 45, 47, 51, 57, 58
5.6, 6.8, 1.2, 6.5, 7.9, 6.5
Mean: 13.5, Median: 14.5, Mode: 13.5 and 15, Outlier: 7 Mean: 52.4, Median: 53, Mode: 53. No Outlier. Mean: 5.8, Median: 6.5, Mode: 6.5. Outlier: 1.2

Section 3.4: Using Formulas
Formula : an equation that shows a relationship between qualities that are represented by variables.
Distance: d = rt
Fahrenheit: F = 1.8C + 32
Perimeter: P = 2 l + 2 w or P = 2( l + w )

Assignment #20
Pages: 164-165: 1-9 All, 12-31 All.
I want you to read each summary at the top of each section.
Make sure you know the definitions to each Key Term at the top of Page 164.

Chapter 3 Review

by Middle School on Oct 06, 2008

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