Round to the nearest thousandth: 5.0099 Warm-Up Round to the nearest thousandth: 5.0099

Practice Rounding Round to the nearest tenth: 5.249 Closer to 5.2 or 5.3? Round to the nearest hundredth: 5.249 Closer to 5.24 or 5.25? Round to the nearest whole: 357.82 Closer to 357 or 358? Round to the nearest hundred: 357.82 Closer to 300 or 400?

Practice Rounding Round to the nearest thousandth: 5.0099 5.010 Must have the last 0 for the thousandths place! Round to the nearest hundredth: 64.284 64.28 Round to the nearest tenth: 10.957 11.0 Must have the last 0 for the tenths place!

Adding and Subtracting Decimals Same idea as with fractions: the denominator (place values) must be common. So, 3.46 + 2.09 is really like 3 + 2 ones + 4 + 0 tenths + 6 + 9 hundredths = 5.55

Multiplying Decimals Easiest to see with the area model. 2.1 • 1.3 Where is 2 • 1? 2 • 0.3? 1 • 0.1? 0.1 • 0.3? 1 + 1 + .1 1 + .3

Proportions A comparison of equal fractions A comparison of equal rates A comparison of equal ratios

Ratios and Rates If a : b = c : d, then a/b = c/d. Example: 35 boys : 50 girls = 7 boys : 10 girls 5 miles per gallon = 15 miles using 3 gallons

To determine proportional situations… Start easy: I can buy 3 candy bars for $2.00. So, at this rate, 6 candy bars should cost… 9 candy bars should cost… 30 candy bars should cost… 1 candy bar should cost… this is called a unit rate.

To determine proportional situations Here’s another. 7 small drinks cost as much as 5 large drinks. At this rate… How much should 14 small drinks cost? How much should 21 small drinks cost? How much should 15 large drinks cost?

Ratios are not the same as fractions The ratio of males to females is 3 : 2. That means 3/5 of the people are male, and 2/5 of the people are female. The mixture is 3 parts water and 1 part green dye. That means that 3/4 of the mixture is water and 1/4 of the mixture is green dye.

We can add fractions, but not ratios One group of 15 people has 2 females for every male. Another group of 32 people has 1 female for every 3 males. What is the ratio of females to males if the two groups combine?

Exploration 6.3 Do the questions for #1.

Homework Due next Tuesday Section 5.4: 2bd, 5bdf, 8, 10ac, 16abcd, 40abc