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Basic Math Skills Review

Basic Math Skills Review. Ratios & Proportions. Ratios. A ratio compares two quantities. You can compare two numbers, like 4 and 9, or two measurements like feet to feet. A ratio can be written in three ways: the fraction bar indicates to

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Basic Math Skills Review

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  1. Basic Math Skills Review Ratios & Proportions

  2. Ratios A ratio compares two quantities. You can compare two numbers, like 4 and 9, or two measurements like feet to feet. A ratio can be written in three ways: the fraction bar indicates to 4 to 9 4 : 9 the “:” indicates to When writing a ratio as a fraction, the quantity mentioned first is the numerator. The second quantity is the denominator.

  3. Ratios • Ratios are not written as mixed numbers. The ratio compares 9 people in a van to 4 people in a car. Written as a mixed number, however, it indicates that the van holds 2¼ more people than the car. • Sometimes a mixed number can be used as part of a ratio. For example, 2 to 2¾. • If you have decimals in a ratio, convert them to whole numbers before simplifying.

  4. Rates • A comparison between two different types units is called a rate. • In a rate, you will often find these key words separating the quantities you are comparing: in for per 5 gallons of paint for $60

  5. Proportions • A proportion states that two ratios or rates are equivalent. • 5 feet is to 12 feet as 15 feet is to 36 feet

  6. Solving a Proportion A US map has a scale of 1 inch to 75 miles. Lake Superior is 4.75 inches long on the map. What is the actual length in miles? (Use x to represent the length.) cross multiply to get: x = 356.25 miles

  7. More Examples In any group of 100 students, you would expect to find 45 students who will specialize in a particular field of science. In a class of 240 graduating seniors, how many would you expect to specialize?

  8. Answer

  9. More Examples Low-fat cheese has 48 calories per ounce. A client who is having his caloric intake measured has eaten 1½ ounces of cheese. How many calories has he eaten?

  10. Answer

  11. NOVA Math Placement Test • The Math Placement test is given in the Testing Center. • There is a review book for the placement exam in the Annandale Library. (CG 3rd Floor) • It’s called Chart Your Success on the Compass Exam. • Brush-up on current skills, go through what you know. • Don’t try to teach yourself anything that you do not know. • Use the list of suggested websites to help you review. • Neither the Math Center nor the Tutoring Center will help you study for the exam.

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