Percentage Increase and Decrease

4 Key excerpts on "Percentage Increase and Decrease"

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  eBook - PDF

  Mathematical Practices, Mathematics for Teachers

  Activities, Models, and Real-Life Examples

  • Ron Larson, Robyn Silbey(Authors)
  • 2014(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  a. What is the percent of decrease from 72 to 18? b. What is the percent of decrease in the student’s test scores? Round your answer to the nearest tenth of a percent. SCORE 98 SCORE 86 Pre-test Post-test 39. Writing Refer to the definitions in Exercises 37 and 38. Can a percent of increase ever be greater than 100%? Can a percent of decrease ever be greater than 100%? Explain your reasoning. 40. Writing Refer to the definitions in Exercises 37 and 38. A number increases by 20% and then decreases by 20%. Will the resulting number be less than, greater than, or equal to the original number? Explain. 41. Simple Interest Simple interest is the money paid or earned only on the principal (the original amount of money that is borrowed or deposited). The formula used to calculate simple interest is I = Prt where I is the simple interest, P is the principal, r is the annual interest rate (in decimal form), and t is the time (in years). a. Calculate the interest earned on a $500 deposit after 4 years at an annual simple interest rate of 4%. b. You borrow $3000 at an 8% annual simple interest rate. What is the amount needed to pay off the entire loan after 2 years? 42. The Percent Proportion Another way to solve for unknowns in a percent problem is to use proportions. In the percent proportion a — w = p — 100 a represents the part, w represents the whole, and p represents the percent in percent form. Use the percent proportion to solve Exercise 34. What are the similarities between using the percent proportion and using the percent equation? What are the differences? 43. Markups: In Your Classroom To make a profit, a store needs to sell products for more than what it pays for the products. This increase from what the store pays to the selling price is called a markup. a. A store pays $25 for a game. The percent of markup is 30%. Write the percent equation for this situation. What is the dollar amount of the markup? b.

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  eBook - PDF

  Contemporary Mathematics for Business & Consumers

  • Robert Brechner, Geroge Bergeman(Authors)
  • 2019(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  The ability of managers to make correct decisions is fundamental to success in business. These decisions require accurate and up-to-date information. Measuring percent changes in business activity is an important source of this information. Percents often describe a situation in a more informative way than do the raw data alone. For example, a company reports a profit of $50,000 for the year. Although the number $50,000 is correct, it does not give a perspective of whether that amount of profit is good or bad. A comparison to last year’s figures using percents might reveal that profits are up 45% over last year or profits are down 66.8% . Significant news! D ETERMINING R ATE OF I NCREASE OR D ECREASE In calculating the rate of increase or decrease of something, we use the same percentage formula concepts as before. Rate of change means percent change; therefore, the rate is the unknown. Once again we use the formula R = P ÷ B . Rate of change situations contain an original amount of something, which either increases or decreases to a new amount. In solving these problems, the original amount is always the base. The amount of change is the portion. The unknown, which describes the percent change between the two amounts, is the rate. R ate of change ( Rate ) = Amount of change ( Portion ) Original amount ( Base ) SECTION III 6-6 b. If $13,300 was charged for all the meals, how much revenue did each type produce? c. If a 20% price increase goes into effect next month, what will be the new price per meal? d. When photographers, florists, DJs, bands, and other outside vendors are booked through your office for events at the hotel, a 5 1 2 % “finder’s fee” is charged. Last year $175,000 of such services were booked. How much did the hotel make on this service? e.

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  Helping Children Learn Mathematics

  • Robert Reys, Mary Lindquist, Diana V. Lambdin, Nancy L. Smith(Authors)
  • 2014(Publication Date)
  • Wiley

    (Publisher)

  These percents should be illustrated with a variety of different situations and models. For example, a rope with 100 disks arranged in multiples of 10 in alternating colors shows 50% of each color. • Can a price increase 150%? • Can a price decrease 50%? • Can a price decrease 100%? • Can a price decrease 150%? Ironically, the understanding of percent requires no new skills or concepts beyond those used in mastering fractions, decimals, ratios, and proportions. In fact, percent is not really a mathematical topic, but rather the application of a particu- lar type of notational system. The justification for teaching percent in school mathematics programs rests solely on its social utility. As is true with decimals and fractions, percents express a relationship between two numbers. Percents are special ratios based on 100 and without a doubt are the most widely used of all ratios. Percent is derived from the Latin words per centum, which mean “out of a hundred” or “for every hundred.” The origin of percent and its major uses are close- ly associated with ratios, fractions, and decimals. Thus, 25% is the ratio 25:100 or 25 100 , which then connects to decimals (0.25) and the fraction 1 4 . When is percent understood? Students understand per- cent when they can use it in many different ways. For instance, if a child understands 25%, he or she can do the following tasks. • Find 25% in various contexts: Cover 25% of a floor with tiles. Determine 25% off the price of a given item. Survey 25% of the students in class. In many such situations, estimates of 25% are not only ap- propriate but essential. • Identify characteristics of 25%: 25% of the milk in a glass is less than half. If 25% of a glass is spilled, then 75% remains. • Compare and contrast 25% with a range of other percents and numbers such as 5%, 50%, 100%, one-fourth, one-half, and 0.25.

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  eBook - ePub

  Analysing Financial Performance

  Using Integrated Ratio Analysis

  • Nic La Rosa(Author)
  • 2020(Publication Date)
  • Routledge

    (Publisher)

  Despite the simplicity and the mathematical integrity of the percentage change technique, however, there are a number of issues that render this method inadequate for the purposes of financial performance measurement and assessment. Importantly, it is rarely understood that the results are affected by two different factors utilised in the calculation. The first of these is the time frame being utilised for the analysis. The second is the size of the base value in comparison to the size of the change in variable value. The following discussion will examine each of these issues and their implications for the measurement and analysis of the financial performance of businesses.

  Percentage changes and inherent context

  In a similar vein to many other measurement scales for physical phenomenon, the mathematical percentage change technique has an element of inherent context. That is, anyone who is informed of a percentage change in a numerical value should instantly recognise the extent of the change by the number associated with the percentage descriptor. It would be difficult for an analyst, armed only with a currency change in the value of a variable, to ascertain the magnitude of the change in the value of that variable. On the other hand, a value that represents the percentage change in the amount of a variable should instantly convey the magnitude of the change in the value of the variable. This will indicate the change, or performance, of that specific variable for that specific period of time to the base value of that variable. This element is a major advancement over simple currency-only techniques.

  This element of inherent context that a percentage change value possesses could be the main reason why it is such a popular technique for assessing and reporting financial performance. Unfortunately, although the percentage change technique ensures an element of inherent context that could assist users of that information in formulating opinions concerning financial performance, the value of this information is severely limited. The reason is that inherent context from the percentage change technique for an individual variable is only specific for that individual variable and becomes less beneficial in a larger data set. Furthermore, although the percentage change can quantify the size of the change in the value of a variable for a period of time, there are several factors (that will be explored in the following sections) that significantly diminish the utility of percentage change outputs.

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