Mathematical+Reflections,+p.+81+-+0910

 Math 7E 31.Jan.2010**
 * A.M


 * // BIG IDEA!  //**

Many important practical and mathematical applications involve comparing quantities of one kind or another; it is important to know which method to use and how we should use them.

ESSENTIAL QUESTION! What methods are there for comparing things?

1 A) Descirbe a situation in which finding a rate is a good stradegy for making comparisons .Tell why you think your situation calls for finding a rate.   A rate is a good strategy for making comparisons because you can compare which rate is better because it is a fixed ratio and easy for comparing.    Ex. 5 lemons for $1.50 OR 10 lemons for $2.00    Therefore you can compare it by saying that 10 lemons is better.     B) Describe a situation in which finding a unit rate is a good stradegy for making comparisons. Tell why you think your situation calls for finding a unit rate. A unit rates is good strategy for making comparisons because you can compare the number of items for how much it is per 1.Turning a rate to a unit rate. Ex. 6 pencils for $3.00 OR 15 pencils for $4.50 Turned to a unit rate: 50 cents for 1 pencil OR 30 cents for 1 pencil Therefore you can see easily that 15 pencils for $4.50 is better. 2.There are 17 girls and 13 boys in Mr.Baldridge’s class.Write every comparison you can think that can be formed from this information.Describe what each comparison shows. Ratio : 17 (girls) : 13 (boys) Percent : 57% girls and 43% boys Fraction: 17/30 students are girls and 13/30 students are boys. 3.Rodrigo dorve his car 400 miles and used 12 gallons of gas.Write two rates that tell about this situation,and explain what each shows. Rate :400 miles by 12 gallons of gas Unit Rate : 33.3 miles per 1 gallon of gas 4.If you know that 4 cans of chilli feed 6 people,how many cans of chili will feed240 people?How many people can you feed with 45 cans of chili?Explain your answers. __ 6 people x 40 people  __ 4 cans x 40 people= 160 cans of chili for 240 people __ 4 cans of chili x11.2  __ 6 people x 11.2= 67 people 5.How do you recognize a situation in which you need to use a ratio comparison rather than simply finding differences? You can recognize a situation like that when it shows you the 2 numbers exact you can compare them by using a ratio. In this investigation we used all types of comparisons such as ratios,percents,fractions and proportions.We learned how t estimate populations and population densities.We used different stradegies and more about this unit.
 * __ Mathematical Reflection 6  __**
 * __ Summary:  __**