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 TOPICS This page:   ratio/proportion    Search   Dr. Math See also the Dr. Math FAQ:   working together Internet Library:   ratio/proportion MIDDLE SCHOOL About Math Algebra    equations    factoring expressions    graphing equations Arithmetic    division    exponents    factorials    factoring numbers    fractions/percents    logarithms Definitions Geometry    2-dimensional      conic sections/        circles      triangles/polygons    3D and higher      polyhedra History/Biography Logic Measurement    calendars/      dates/time    temperature    terms/units Number Sense    factoring numbers    negative numbers    pi    prime numbers    square roots Probability Puzzles Ratio/Proportion Statistics Word Problems Browse Middle School Ratio/Proportion Stars indicate particularly interesting answers or good places to begin browsing. Selected answers to common questions:     Mixture problems.     Unit conversions, unit cancellation.     What is a ratio? Radius of a Sphere [01/29/1998] What is the ratio of the areas and volumes of two spheres, one with radius 3 times the other? What possible theorems are suggested? Raising the Antifreeze Ratio [08/07/99] A 5-gallon radiator containing a mixture of water and antifreeze is supposed to contain a 50% antifreeze solution... Ratio and proportion [12/5/1994] I need extra help in ratio and proportion. Ratio and Proportion [7/4/1996] Six men can complete a piece of work in one day... 44 men can build a tower in 5 days... Ratio and Proportion: Beaches and Hawks [10/26/1998] On a map, the scale states that 3 inches represent 125 miles. Two beaches are 5.2 inches apart. How far apart are they in miles? Ratio and Proportion: Jobs [7/7/1996] 30 men can complete a job in 12 days at 8 hours/day. How many hours/ day will it take to complete the job in 10 days with 24 men? Ratio of Anti-Freeze to Water [7/28/1996] How much water should I add to a gallon of anti-freeze to make a 60/40 solution? Ratio of Apples to Pears to Oranges [09/13/2002] If the ratio of apples to pears to oranges is 7:8:10, how many pears are there if the total number of fruits is 500? Ratio of Greek to Latin Exams [06/10/2003] Susanna's average score on all exams was 88. On Greek exams it was 80, and on Latin exams 92. What is the ratio of the number of Greek exams to the number of Latin exams? Ratio of Ore to Copper [9/4/1996] Ore contains 2 percent copper. How much ore is needed to obtain 24 tons of copper? Ratio of Rates and Work [06/06/1998] Given the rates of 5 semi-skilled and 4 skilled workers, can you find how long it takes 1 semi-skilled and 2 skilled workers to do a job? Ratio of Ratios [06/05/2002] In a community, 3/5 of the men are married to 2/3 of the women. What fraction of the residents are married? Ratio of Sides and Ratio of Areas [02/11/1999] If the sides of a triangle are in the ratio of 1:7, what is the ratio of their areas? What about for other shapes? Ratio of Volume to Surface Area in Humans [12/09/1999] What is the healthy ratio of volume to surface area for humans? The Ratio of Water to Wine [10/22/1995] A cask is filled with 45 gallons of wine. Nine gallons are removed and the cask is refilled with water. The nine gallons of the mixture are removed and the cask is again refilled with water. What is the ratio of water to wine in the final mixture? Ratios and Fractions: A Reconciliation [04/02/2013] Teachers disagree about whether a fraction can compare part to part. Doctor Peterson first distinguishes between ratios and fractions before reconciling them and warning against inflexible thinking. Ratios and Geometry [10/29/1998] An airplane flying at 33,000 feet has a visibility of 100 miles. What percent of the total land area to the horizon is visible? Ratios and Mixtures [05/10/2001] Sue needs to mix up a potion for her client... in what ratio must Sue mix the honey and turpentine? Ratios and Proportions in Everyday Life [05/13/2002] How are ratios and proportions used in everyday life? Ratios and Their Relative Benefits [03/04/2016] Why use a ratio to compare numbers, rather than just subtracting them? By taking one example to extremes, and considering units, Doctor Peterson explains the advantages of proportional reasoning. Ratios Between Keys on a Piano [11/05/1997] I know that there is a formula to describe a ratio from one key to another but I can't find it... Ratios Containing a Zero [07/03/2005] What does the ratio 1:0 mean? What does the ratio 0:1 mean? Are they meaningless? Ratio Set-Up Problem [09/02/2003] Concrete can be made by mixing cement, sand, and gravel in the ratio 3:6:8. How much gravel is needed to make 850 m^3 of cement? Ratios: Second Number [01/04/1998] What does the second number in a ratio stand for? Recipes and Adjusting Ingredient Amounts [04/20/2005] In a recipe, 5 1/2 cups of coconut uses 14 ounces of milk, but I only have 4 cups of coconut, so how many ounces of milk do I use? Rule of Three [06/15/2002] Please explain to me briefly (and with an example) the concept of the rule of three. Scale Factor Acrobatics [07/15/2014] A homeschooled teen struggles to make headway with a word problem in two unknowns. After emphasizing the scale factor in their ratio, Doctor Ian models the scenario algebraically. Scale Factor of Similar Shapes [05/12/2000] Find the scale factor, the ratio of the perimeters, and the ratio of the areas of two regular octagons that have sides of lengths 21 and 28, respectively. Scaling up from a Numerator and Denominator to a Triple Ratio [07/08/2011] A student familiar with fractions struggles to put more than two unknowns into one proportional relationship. Doctor Jerry sets up equations to represent the scale factors. Setting up Proportions [03/11/2010] Doctor Peterson explains how a proportion resembles a table of data, and shows a seventh grader how to spot mistakes when setting up relationships between ratios. Sides of Similar Triangles [06/11/1998] The sides of a triangle are 24, 16, and 12. The shortest side of a similar triangle is 6. Find the longest side of this triangle. Similar Rectangles [05/03/1997] The outside boundary of an unfolded card is similar to its boundary when it is folded. Find the width of the card if the open length is 8 and the folded length is 4. Single Variable Algebraic Mixture Problem [05/03/2005] Brittany needs a mixture of 76% oats and 24% corn. She currently has 25 pounds of a mixture that is 28% oats. How many pounds of oats should be added to the mixture? Skilled and Semi-Skilled Workers [09/04/2002] Four skilled workers do a job in 5 days, and five semi-skilled workers do the same job in 6 days. How many days will it take for two skilled and one semi-skilled worker to do that job? Solving a Ratio Problem [02/06/2006] There are 33 red and yellow counters in a container. The ratio of red to yellow is 3 to 8. How many of each color are in the container? Tea and Cakes [11/13/2002] A cafe sold tea at 30 cents a cup and cakes at 50 cents each. Everyone in a group had the same number of cups of tea and the same number of cakes. The bill came to \$13.30. How many cups of tea did each person have? Triangle and Trapezium Ratio [10/26/1998] ABCD is a square with sides of length 4 cm. Find M on BC so that the ratio of triangle ABM and trapezium ADCM is equal to 1/3. Turning a Perimeter into a Scale Factor [02/17/2003] Perimeter and area ratios of similar figures are given. Find each scale factor. Two Numbers in 5:3 Ratio [12/07/2002] Two numbers have a ratio of 5:3. The larger number is 36 more than half the difference of the two numbers. What are the two numbers? There are two pairs of numbers that will make this a true statement. You need to find both of them. Using a Diagram to Find a Formula [11/13/2002] A bag contains green, yellow and orange marbles. The ratio of green to yellow marbles is 2:5. The ratio of yellow to orange marbles is 3:4. What is the ratio of green marbles to orange marbles? Page: []

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