*is another way of writing a ratio when the second term of the ratio is 100.*

**Percent***comes from the Latin words*

**Percent***pars per centum*

*meaning parts per hundred. We use*

**%**to express percent.

Example:

18/100 = 18%

25/100 = 25%

If the denominator is not 100, multiply the numerator and the denominator with the same number which will make the denominator equal to 100.

Example:

4/5 =4/5 x 20/20 = 80/100 or 80%

1/2 = 1/2 x 50/50 = 50/100 or 50% means half of whole

1/10 = 1/10 x 10/10 = 10/100 or 10% means 1 part of a whole

1/4 = 1/4 x 25/25 = 25/ 100 or 25% means quarter of a whole

3. Converting Percent to Decimal to Fraction |

Fraction to Decimal to Percent
3/40 = 0.075 = 7.5%
to
decimal
divide
3/40 = .075
to
percent
move the
decimal point 2 places to the right and add the percent % sign
0.075
= 7.5%
Decimal to Percent to Fraction
0.0064 =
0.64% = 0.0064/10000 or 4/625to
percent
move the
decimal point two places to the right and add the percent sign %
0.0064
= 0.64%
to
fraction
multiply both the top and bottom by 10
for every number after the decimal point
0.0064/1 x 10 000 /10 000 = 64/ 10 000 or 4/625
Percent to Decimal to Fraction
75% = 0.75 = 75/100 or 3/4
to
decimal
move the decimal point 2 places to the
left and remove the % sign
75% = 0.75
to
fraction
75/100 = 3/4
4. Finding Percent of a number solve: a. 20% of 60 Mental Math Calculator 100% of 60 is 60 convert 20% to decimal 10% of 60 is 6 20% is 0.20 20% is 10% + 10% multiply 0.20 by 6010% + 10% = 6 + 6 0.20 x 60 = 12 20% = 12 b. 0.1% Mental Math Calculator
100% of 40 is 40 convert 0.1% to decimal 10% of 40 is 4 0.1% is .001 1% of 40 is 0.4 multiply .001 by 40 0.1% of 40 is 0 .04 0.001 x 40 = 0.04 0.1 % of 40 = 0 .04c. 250% of 400 Mental Math Calculator 100% of 400 is 400 convert 250% to decimal 50% of 400 is 200 ( 400/2) 250% is 2.50 250% is 100% + 100% + 50% multiply 2.50 by 400 100% + 100% + 50% = 400 + 400 + 200 2.50 x 400 = 1000 250% of 400 = 10005. Combining Percents* Discount is a deduction from the usual cost of something. * Sale Price is the price of a good service that is being offered at a discount.
* Total price with taxes is the total amount and tax charges for all items being purchased.
Example: * A herd of caribou was moved to a new location. The population increased by 10% the first year and then increased by 20% the second year. a. Find the population after the second year. b. Explain why there was not 30% increase in population over two years. Solution: a. Population of caribou is 100 increase in first year is 10% 10% of 100 or 0.10 x 100 = 10
population of caribou after one year is
100 + 10 = 110 New population of caribou ( after one year) is 110 increase in second year is 20% 20% of 110 or 0.20 x 110 = 22 population of caribou after second year is 110 + 22 = 132b. There was not a 30% increase in population over two years because after a year, the population increased by 10% , it became 110 and this new population was increased by 20% which gave a total population of 132 caribou after the second year. If population was increased by 30% over two years, the original population 100 will be increased by 30% which will result to 130 population. *Show you know* What is the final price at each store. Which is the better buy? Explain your thinking.Store A: 50% one day only Store B: 25% off one day, followed by 25% off the reduced price the second day. Example:Store A : 50% of $200 (one day only) 0.50 x 200 = 100 Find the discount price: 200 - 100 = 100 The discount price is $100.Store B: 25% discount of $200 on the first day 0.25 x 200 = 50 Find the discount price $200 - 50 = 150 The discount price after the first day is $150. The discount on the sale price the second day is 25% of $150. 0.25 x 150 = 37.5 Find the discount price: $150 - 37.5 = $112.50 The final discount price after the second day is $ 112.50. *** Store A gives the better buy than store B. The 25% discount followed by another 25% is not the same as 50% discount from the original price because the discount on the second day is only 25% of $150 and not 25% of $200. The original price is $200. The selling price after two 25% discount is $112.50$200 - $112.50 = $87.50 $87.50 ÷ 200 = 0.4375 or 0.44 which is 44%*** The total discount offered by store B is 44% which is less than 50% discount offered by Store A, therefore Store A gives the better buy. Video that will help us understand how to find a percent of a number. |

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