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(Ch. 11) GRE Ratios and Math Formulas Review
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Terms in this set (16)
Percent Increase
(Increase / Original) × 100%
Percent Decrease
(Decrease / Original) × 100%
Profit
seller's price - cost to seller
Percent of selling price that is profit
(Profit / original selling price) × 100%
Discount
original price - reduced price
Percent discount
(Discount / Original price) × 100%
Sale price
final price after discount or decrease
Interest
a percent per unit of time (ex. 5% per month)
Principal
sum of money invested
Simple interest
the interest payments received are kept separate from the principal
Compound interest
the money earned as interest is reinvested and the principal grows after every interest payment received
Rate of speed formulas (3)
Speed = distance / time ;
Time = distance / speed ;
Distance = (speed)(time)
Combined Rates Problems
Rates can be added. Combined Rate = Rate₁ + Rate₂
Combined Work Formula
Proportions can be used to find out how long it takes a number of people (or machines) working together to complete a task. (1/a) + (1/b) + (1/c) = (1/Total) -- (can have as many parts as necessary)
**Combined: T = ab / a+ b**
Average formulas (3)
Average = sum of terms / # of terms ;
# of terms = sum of terms / average ;
Sum of terms = (# of terms)(average)
Weighted Average Formula
Weighted Avg = #₁(Avg₁) + #₂(Avg₂) / # of terms (total)
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