Mrs. Disponzio's Math Website



Mrs. Disponzio’s Math Formula SheetCircumference of a Circle: C = πd Diameter = 2RArea of a Circle: A=πr2 Radius = 12(D)Percent Increase or Decrease: DifferenceOriginal (start)Percent Error: DifferenceActual( What you should get) Exam states calculate percent error, increase or decrease. Scale Factor: Large (Feet)Small (Inch) Ex: 12 Feet per inchSolving For Model or Actual: Larger Unit Smaller Unit = Scale Factor1Interest: I = PRT R = when solving for R convert to a %When substituting in for R convert to a decimalCurrent balance/Bank account balance today = Interest + principalDiscount: What you pay for an item is under a 100%.20% is the actual discount on the item. Expression = .20x 80% is what you paid for the item after the discount. Expression = .80xCommission: Discounts are applied first. NO COMMISSION ON TAX.40% commission on all sales (x). Expression: .40xIncreased current commission by 30%. Expression: 1.30x Tax: Discounts are always applied first then subtracted (-). Taxes are calculated from sales price then added (+) to the sales price.$200 jacket, 20 percent discount, 10 percent tax. Discount: 200 * .20 = $40 Sales Price: 200- 40 = $160 Tax: 260 *.10 = $16. Final Price: 160 + 16 = $176$107 including a 9% tax. What is the original price?107x = 109100Tip: Either before tax or after tax.20% tip before 8% tax was added to a $100 bill.Tip: 100 * .20 = $20 Tax: 100 x .08 = $8 Final Bill: 100 + 20 + 8 = $12810% tax added to a $200 bill. A 20% tip was added after tax was applied. Tax: 200 * .10 = $20 Bill Including Tax: 200 + 20 = $220 Tip: 220 * .20 = $44 Final Bill: 220 + 44 = $264 $140 bill including a 10% tip. What was the bill before the tip was added? 140x = 110100Factoring an Algebraic Expression:Look for the greatest GCF.Look to see if each term has the same variables.Pull out the variable with the lowest exponent.4x2y + 8xm = 4x(xy+2m) Dividing with Exponents (same power): x1x1 = x1-1 =x0= 1 Dividing with Exponents (different powers): x4x2 = x4-2 = x2Inequalities: At least: ≥ At most: ≤ Have only $50: ≤Nicks wants to buy an item for $200. How long will it take him to save if he makes $55 a week? Inequality: 55x ≥ 200Inequality (Special Rule): -5X < 20 = x > -4Flip sign when there is a negative coefficient Markup: RetailWholesale = Retail % = Markup % + 100 %100%The total population increased by 35%. Expression: 1.35xThe current population is 200 and increased by 29%. Expression: 200(1.29)Markup Percent: Retail % - 100%Markup Percent: 150 % - 100%=50%Markup amount: Retail Price – Wholesale PriceRetail Price of $100 - Wholesale price of $50 = $50 Markup ................
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