# Fractions and percentages

• Created by: Rubyblu
• Created on: 10-04-18 16:57
equivalent fractions
two or more fractions that represent the same part of a whole
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changing a fraction into a decimal
by dividing the numerator by the denominator (e.g. 3/8 = 3 / 8 = 0.375
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changing a percentage into a fraction
but the percentage over 100 (e.g. 32% = 32/100 = 8/25)
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changing a percentage to a decimal
divide the decimal by 100 (e.g. 65% = 65 / 100 = 0.65)
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changing a decimal into a percentage
multiply the decimal by 100 (e.g. 0.43 = 0.43 x 100 = 43%)
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changing a fraction into a percentage
multiply the denominator until you get 100, then multiply the numerator by the number you multiplied the denominator by, then use the numerator as the percentage (e.g. 2/5 = 40/100 = 40%)
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changing a decimal into a fraction
by using a place-value table (e.g. 0.32 = 32/100 = 8/25)
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calculating the percentage of a quantity
by using a multiplier (e.g. 10% of 54kg = 10% = 0.1 so 10% of 54 = 0.1 x 54 = 5.4kg)
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increasing by a percentage
by using a multiplier (e.g. increase \$6.80 by 5% = 100% + 5% = 105% = 1.05 so \$6.80 x 1.05 = \$7.14)
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decreasing by a percentage
by using a multiplier (e.g. decrease \$8.60 by 5% = 100% - 5% = 95% = 0.95 so \$8.60 x 0.95 = \$8.17)
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expressing a quantity as a percentage
by setting up the fraction and multiplying by 100 (e.g. express \$6 as a percentage of \$40 = 6/40 x 100 = 15%)
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percentage change
percentage change can be used to calculate percentage profit or percentage loss; percentage change = change/original amount x 100
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percentage profit
Jake buys a car for \$1500 and sells it for \$1800, what is his percentage profit?; percentage profit = 300/1500 x 100 = 20%
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percentage loss
Mia bought a pair of shoes for \$30 but only sold them for \$15, what is her percentage loss?; percentage loss = 15/30 x 100 = 50%
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simple interest
the interest earned or charged on a loan
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simple interest example
Erin has a loan of \$500 and she agrees to pay 1.6% interest each month, how much would she own after 6 moths?; 6 x 48 = \$48 in interest + \$500 loan = \$548
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compound interest
the interest paid on the original principal and on the accumulated past interest
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compound interest example
Elizabeth invests \$400 into a savings account, and the account pays her 6% interest every year, so how much money will she have in the account after 3 years?; 100% + 5% = 105% = 1.05 so 400 x 1.06 = \$424 = 1 year
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compound interest example II
424 x 1.06 = \$449.44 is 2 years so 449.44 x 1.06 = 476.41 (rounded) = 3 years
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formula for compound interest
value of investment = P( 1 + r/100) ^ n (P is the initial investment, r is the annual percentage rate, and n is then number of years)
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reverse percentage
involves working backwards from the final amount to find the original amount using a multipliern
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reverse percentage example
in a sale the price of a freezers reduced by 12%, and the sale price is \$220, so what was the price before the sale?; A decrease of 12% gives a multiplier of 0.88, and by dividing the sale price by the multiplier, you get 220 / 0.88 = \$250
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## Other cards in this set

### Card 2

#### Front

by dividing the numerator by the denominator (e.g. 3/8 = 3 / 8 = 0.375

#### Back

changing a fraction into a decimal

### Card 3

#### Front

but the percentage over 100 (e.g. 32% = 32/100 = 8/25)

#### Back ### Card 4

#### Front

divide the decimal by 100 (e.g. 65% = 65 / 100 = 0.65)

#### Back ### Card 5

#### Front

multiply the decimal by 100 (e.g. 0.43 = 0.43 x 100 = 43%)

#### Back ## Comments

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