1. More Science Skills: Scientific Notation and Ratios September 8, 2008

2. Scientific Notation Helps you write very large or very small numbers in an easier way! Using the power of 10, you can rewrite numbers… Very small numbers will have a negative notation Very large umbers will have a positive notation. For example: 4 X 10 4 = 40,000 12 X 10 12 = 12,000,000,000,000

3. More examples: 4,650,000 = 4.65 X 10 6 3 X 10 -4 =.0003 1 X 10 -1 =.1 1.7 X 10 -9 =.0000000017

4. Let’s Practice: A. 4.64 X 10 2 B. 6.43 X 10 -6 C. 8.9 X 10 -7 D. 4.3 X 10 6

5. Writing in Scientific Notation:.0032 = 3.2 X 10 -3 1,000000 = 1 X 10 6.01 = 1 X 10 -2 71,000,000,000 = 7.1 X 10 10

6. Ratios and Proportions It’s important to know how to use ratios and proportions when working with different units of measurement. The ratio of A to B is written as: A:B or A/B

7. Ratios and Proportions: RATIO is two (often different) things compared to each other, or the relationship of 2 numbers. Proportion s show the equality between 2 ratios. Ex. 3 dollars per gallon. 40 miles per 1 hour. 15 girls versus 14 boys. 23 green balls versus 41 blue balls

8. Ratios: Comparing 2 quantities: A wall is 96 cm high and a pencil is 8 cm long Divide 8 into 96…it would take 12 pencils to equal the height of the wall. Therefore the ratio of the wall to a pencil is 1 to 12 1:12 1/12.

9. Let’s Practice Ratios: The ratio of triangles to circles is 3:4, or 3/4 The ratio of triangles to squares is 3:6, or 3/6 The ratios of circles to squares is 4:6, or 4/6

10. For example: Last year, 78 girls and 52 boys were enrolled in Earth Science. What is the ratio of girls to boys? Girls : Boys is 78:52, or 78/52 What is the ratio of boys to girls? Boys : Girls is 52:78, or 52/78

11. Sample Problem 1: 1. The fish tank is home to 21 sharks. Ratio of males to females is 3:4. How many males? 9 Males How many females? 12 Females

12. Sample Problem 2 2. Cam’s Pet Shop has 92 rabbits. The ratio is 1:4, black to white. How many white? 74 How many black? 18

13. Sample Problem 3: 3. Farmer Frank raises pigs. He ahs a total of 142 pigs. The ratio of male to female is 3:4. How many females? 81 How many males? 61

14. Sample Problem 4: 4. Mrs. Jonson’s class has 67 students. The ratio is 3 to 2. How many girls were in the class? How many boys? 27 How many girls? 40