Chapter 6, Section 6: Proportions and Percents December 11, 2008

Warm Up: Percent  Fraction (SF) 65% Percent  Fraction (SF) 0.4% MATHEMATICS P(one of the letters that occurs more than once):

Percent  Fraction (SF) 65%

Percent  Fraction (SF) 0.4%

MATHEMATICS P(one of the letters that occurs more than once):

Percent  Proportion Drawing a model can help solve percent problems. Like finding 75% of 40. 0% 0 75% 30 40 100% Part Whole Draw a model of 0 to 40. Then divide the model into 4 sections and color in 3 of the 4 sections. You can also make a proportion. 75/100 = 30/40

Drawing a model can help solve percent problems. Like finding 75% of 40.

Example 1 Find 65% of 245. 0% 0 100% 65% 245: Whole n  part 65/100 = n/245 (Write a proportion) 65(245) = 100n (Cross Product) 65(245)/100 = n (Division Prop. Eq. n = 159.25 159.25 is 65% of 245.

Find 65% of 245.

Now, Do It Without Drawing 25% of 124 is ____ 43% of 230 is ____ 12.5% of 80 is ____ 31 98.9 10

25% of 124 is ____

43% of 230 is ____

12.5% of 80 is ____

What Percent of a # is #? Example: What Percent of 60 is 52? Therefore, 52 is what Percentage of 60? It’s the same process and set up, just make sure you know where your unknown goes!!! 52/60 = x/100 (remember that percent is fraction with a denominator of 100). (cross product) (simplify) (solve)

Example: What Percent of 60 is 52?

Therefore, 52 is what Percentage of 60?

It’s the same process and set up, just make sure you know where your unknown goes!!!

Determine Percentage, to 10 th of a Percent What percent of 250 is 138? 14 is what percent of 15?

What percent of 250 is 138?

14 is what percent of 15?

Finding Whole Amounts. When you know PERCENT that a part represents, and you want to FIND the WHOLE AMOUNT. Our class fundraising committee might announce, “We’ve collected $207 so far, which is 46% of our goal!” Use proportions to calculate the goal.

When you know PERCENT that a part represents, and you want to FIND the WHOLE AMOUNT.

Our class fundraising committee might announce, “We’ve collected $207 so far, which is 46% of our goal!”

Use proportions to calculate the goal.

Figure This One Out. 207 is 46% of what number?

207 is 46% of what number?

Try These Too 19 is 75% of what number? 310 is 99% of what number? 25.3 313.1

19 is 75% of what number?

310 is 99% of what number?

Word Problem In 1998, the number of drive-in movie screens in the United States was only about 21% of the number in 1980. About how many drive-in screens were there in 1980? 3,560 Estimated 748 1998 915 1990 ? 1980 Number of Screens Year

In 1998, the number of drive-in movie screens in the United States was only about 21% of the number in 1980. About how many drive-in screens were there in 1980?

One More Drive In Question In 1990, the number of drive-in movie screens was about 32.4% of the number in 1985 (the year I was born). Find the number of drive-in screens in 1985. 2,824 Screens 748 1998 915 1990 ? 1980 Number of Screens Year

In 1990, the number of drive-in movie screens was about 32.4% of the number in 1985 (the year I was born). Find the number of drive-in screens in 1985.

Assignment #47 Page 308: 1-33 All.

Page 308: 1-33 All.