advertisement

Section 3.7 – Relating Fractions, Decimals and Percents Percent - number out of 100. It is the numerator of a fraction which has a denominator of 100 We know that 0.63 = Therefore it is 63%. Example 1: Write the following percents as fractions out of 100 (reduce if possible) and as decimals. a) 5% = ÷5 = b) 17% = = 0.17 c) 50% = ÷50 = d) = = 0.333 = 0.05 Example 2: Write each as a fraction over 100 and then as a percent. a) x 10 = = 20% b) x2= = 34% c) x4= = 80% d) = e) f) = 85% = 0.35 = = 17.7% = 35% Let’s consider benchmarks 100% - is all so 1 75% - is three quarters (3/4) so 0.75 50% - is half (1/2) so 0.5 25% - is a quarter (1/4) so 0.25 Example 3: Why is 70% not a good estimate for 35 out of 80. is 50% so is less than 50%. So it does not make sense to be 70%. Example 4: Explain how you would estimate the percentage when a test score is 26 marks out of 55. Its approximately 25 out of 50 which is 50% Example 5: Determine the percent of a book that is left to read if the class has read 60 out of 150 pages. Explain your thinking. Read = 0.4 = 40% So full book is 100% - 40% = 60% left to read Example 6: Change each fraction to a percent then a decimal Fraction a) x2 = Percent x 10= Decimal 40% 0.40 b) x4 = 80% 0.80 c) x2 = 12% 0.12 d) x5 = 35% 0.35 75% 0.75 e) x 25 = Example 7: Place each number in question 6 on number line 0% 12% 25% 35% 40% 50% 75% 80% 100%