Chapter 3 ReviewBest 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.

• 58.659

• 32.876

• .87324

• .00649

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 miles². Lake Erie, the smallest of the Great Lakes, has an area of 9,920 miles². 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 = 2l + 2w 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.