Pre-Algebra Chapter 3

Decimals and Equations

3.1 Rounding and Estimating

3.1 Rounding and Estimating• Rounding to Estimate: Round to same place value before estimating

• Front-end Estimation: Add front numbers before you estimate the remaining digits

• Clustering Estimation: if all numbers are clustered around the same number round and multiply by the number of items in list

3.2 Estimating Decimal products and Quotients

Estimate the product

3.2 Estimating Decimal products and Quotients

Estimate the Quotient by using Compatible numbers.Compatible numbers are numbers that are easy to divide mentally

1. Round the divisor2. Round the dividend to a compatible number

3.3 Mean, Median, & Mode• Mean: is the sum of the data values divided by the

number of data values. *Hint Average

• Mode: is the data item that occurs most often in the list. *Hint MOde = MOst

• Median: is the middle number when the numbers are listed in numerical order. *Hint Middle

• Range: is the difference between the greatest and lowest numbers in the set of data

• Outlier: is a data value much greater or less than the other data values. *Hint it affects the mean

Examples 3.3Find the measures of central tendency for the following list of data:42, 59, 48, 50, 50 , 45 200

Mode:Median:Range:Outlier:Mean:

3.4 Using FormulasA Formula is an equation that shows a relationship between quantities that are represented by variables.

Examples 3.4

a. P=88.2 cm b. P = 52in

Think of peRIMeter as the distance around the “RIM” of a figure.

3.5 Solving Equation by adding and Subtracting Decimals

Same as if you were solving equations by adding and subtracting integers.

3.6 Solving Equations by multiplying or dividing Decimals

a) y÷(-3.9) = -55.99 b) 2.3x = -4.37

Same as if you were solving equations by Multiplying and Dividing integers.

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3.7 Metric System

eka

ecko

base

enti

illi

eci

Base Units: Meters, Grams, or Liters

3.7 continued

3.8 Problem Solving by Acting it out

Underconstruction