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

Preview of the back of card 3

Card 4

Front

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

Back

Preview of the back of card 4

Card 5

Front

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

Back

Preview of the back of card 5
View more cards

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