Lesson 3 Equivalent Rational Numbers

Rational Number A rational number can be expressed as a fraction or mixed number, a decimal or a percent. We will cover rational numbers more in a few lessons.

Example 1 How would 14/16 be expressed as a decimal? First, how do you change a fraction to a decimal? –Divide the numerator by the denominator. (Flower story) 14 ÷ 16= So, 14/16 =.0875

Example 2 If 1 out of 3 students in class plays a musical instrument, what percent of the students in her class play a musical instrument? First, change the fraction 1/3 to a decimal. Then, take the decimal … and move the decimal point 2 places to the right to make it a percent. (It is the same as multiplying by 100) 33.3% of the students play a musical instrument.

Example 3 The population growth of Melvin’s city from 1950 to 2000 was 325%. How could 325% be expressed as a mixed number? All percents are out of 100, so we would rewrite 325% to be 325/100. That is an improper fraction. Now, we change the improper fraction to a mixed number. 325/100 = 3 25/100 = 3 1/4

Example 4 Jill’s savings bond earned 0.5% interest. How would 0.5% be expressed as a decimal? To change a percent to a decimal, move the decimal point to the left 2 places (it is the same as dividing by 100). So, 0.5= 0.005

Lets Practice Forty five percent of the students in town take the bus to school. What fraction of students take the bus to school? In a recent election, 2/5 of the registered voters actually voted. What decimal is equivalent to 2/5? What percent is equivalent to 0.001? Luther received a 4.5% raise in his salary. What decimal is equivalent to 4.5%?

More Practice A survey found that 2/3 of the 8 th grade students plan to take Spanish in high school. What percent of the 8 th grade place on taking Spanish in High School? What decimal is equivalent to 0.08%? A technology company’s profits are up 225% from last year. Which decimal is equivalent to 225%? Mr. Simmons enlarged a photo by 150%. What mixed number is equivalent to 150%?

Explain yourself Frank read that argon makes up 0.9% of the Earth’s atmosphere. –Express 0.9% as a decimal. –Explain how you found your answer and show your work. –Hand this open ended response in when you are finished.