# PSU MATH 034 - BASIC PRINCIPLE MARGIN (11 pages)

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## BASIC PRINCIPLE MARGIN

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## BASIC PRINCIPLE MARGIN

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Lecture Notes

Pages:
11
School:
Pennsylvania State University
Course:
Math 034 - The Mathematics of Money

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Basic Principles Margin 0 2 Item Pricing Markup vs 0 1 Percentages Percent Increase Decrease The word percent literally means per hundred A number followed by a percent sign is to be interpreted as a ratio or fraction per hundred For example 4 stands for 4 out of 100 Calculating Percentages of a Number r of N r 100 N r N 100 Example 1 Compute 6 of 200 Solution 6 of 200 6 100 200 6 200 100 12 Note in the above example that 6 means 6 per hundred which written a fraction is 6 100 This fraction can be written as the decimal 06 so 6 can be ought of as the decimal 06 or 6 06 Calculating Percentage r To find the percentage r that A is of B r A B 100 Example 2 What percent is 18 out of 250 Solution r 18 250 100 So r 6 2 Calculating Percentage Increase Example 3 What percent is 56 out of 140 To find percentage r that an initial amount A increased to B Solution r 56 140 100 100 r net increase initial amount So r 40 r B A A 100 r B A 1 100 r ending amount initial amount 1 100 Basic Principles Margin 0 2 Item Pricing Markup vs Example 4 Standardized test scores at Happy Valley High School have increased from 840 to 920 Find the percentage increase Solution r 920 840 1 100 So r 9 52380952 Example 5 John Henry s salary increased from 45 810 to 46 974 Find the percentage increase in his salary Solution r 46974 45810 1 100 r 2 54092993 So r 2 54092993 Example 6 In one year gas prices rose 40 If the current price is 3 39 per gallon find the price per gallon one year ago Solution In this problem we are given the percentage increase and B we need to find A Since r 40 and B 3 39 we have 40 3 39 A 1 100 or 40 3 39 A 1 100 Basic Principles Margin 0 2 Item Pricing Markup vs We first divide by 100 40 100 3 39 A 1 Then add 1 40 100 1 3 39 A Next multiply by A A 40 100 1 3 39 We simplify the term in the parentheses A 1 4 3 39 Finally we divide by 1 4 A 3 39 1 4 2 421 142857 Since A is a dollar figure we round A 2 42 The formula for percentage increase also works for decreases the formula

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