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tsbasic5e_ppt_3_7

VIEWS: 15 PAGES: 8

									 § 3.7

Estimating and Solving Applied
   Problems Using Decimals
    Estimating with Decimals
Example: Estimate 238,598 + 487,905.
   238,598 + 487,905  200,000 + 500,000 = 700,000


Example: Estimate 68,976  0.875.
   68,976  0.875  70,000  0.900 = 63,000


Example: Estimate 34.5684 ÷ 0.55.
   34.5684 ÷ 0.55  30 ÷ 0.60 = 50


                                                          Angel, Elementary Algebra for College Students, 6e, # 2
                  Tobey & Slater, Basic College Mathematics, 5e - Slide #2
     Problem Solving Steps
1.   Understand the problem.
      a)   Read the problem carefully.
      b)   Draw a picture if this is helpful.
      c)   Fill in the Mathematics Blueprint so that you have the
           facts and a method of proceeding in this situation.
2.   Solve and state the answer.
      a)   Perform the calculations.
      b)   State the answer, including the unit of measure.
3.   Check.
      a)   Estimate the answer.
      b)   Compare the exact answer with the estimate to see if
           your answer is reasonable.


                                                               Angel, Elementary Algebra for College Students, 6e, # 3
                       Tobey & Slater, Basic College Mathematics, 5e - Slide #3
  Mathematics Blueprint
The Mathematical Blueprint is simply a sheet of paper with
four columns. Each column tells you something to do.

 Mathematics Blueprint for Problem Solving
 Gather the    What Am I                 How Do I                         Key Points to
 Facts         Asked to Do?              Proceed?                         Remember




                                                            Angel, Elementary Algebra for College Students, 6e, # 4
                    Tobey & Slater, Basic College Mathematics, 5e - Slide #4
   Mathematics Blueprint
Example:
Kelsey is making holiday cookies, which she will give as gifts to her
friends and co-workers. She has made 34.5 pounds of cookies,
which need to be divided up into equal packages containing 0.75
pound of cookies. How may packages can Kelsey make?

 Mathematics Blueprint for Problem Solving
 Gather the       What Am I                 How Do I                          Key Points to
 Facts            Asked to Do?              Proceed?                          Remember
 There are 34.5   Find the number Divide 34.5 by                              Move the decimal
 lbs of cookies   of packages      0.75.                                      point over two
 and each package Kelsey can make.                                            places before
 is 0.75 lb.                                                                  dividing.

                                                                                Example continues.
                                                                Angel, Elementary Algebra for College Students, 6e, # 5
                        Tobey & Slater, Basic College Mathematics, 5e - Slide #5
   Mathematics Blueprint
Kelsey is making holiday cookies, which she will give as gifts to her
friends and co-workers. She has made 34.5 pounds of cookies,
which need to be divided up into equal packages containing 0.75
pound of cookies. How may packages can Kelsey make?

 34.5  0.75  the number of packages
                        46
 0.75 34.5     0.75 34.50
                     300
                                Kelsey can make
                      450       46 packages.
                      450
                         0

                                                               Angel, Elementary Algebra for College Students, 6e, # 6
                       Tobey & Slater, Basic College Mathematics, 5e - Slide #6
   Mathematics Blueprint
Example:
David bought apples and pears at the grocery store for a fruit salad. At the
checkout counter, the apples weighed 2.7 pounds and the pears weighed 1.8
pounds. If the apples cost $1.29 per pound and the pears cost $1.49 per pound,
how much did David spend on fruit? (Round your answer to the nearest cent.)


 Mathematics Blueprint for Problem Solving
 Gather the           What Am I                  How Do I                          Key Points to
 Facts                Asked to Do?               Proceed?                          Remember
 2.7 lbs of apples    Find the total cost Apples: multiply                         Multiplication
 costing $1.29/lb.;   David spent on      2.7 by 1.29;                             comes before
 1.8 lbs of pears     the fruit.          Pears: multiply                          addition.
 costing $1.49/lb.                        1.8 by 1.49; Add
                                          the two products.

                                                                                     Example continues.
                                                                     Angel, Elementary Algebra for College Students, 6e, # 7
                             Tobey & Slater, Basic College Mathematics, 5e - Slide #7
  Mathematics Blueprint
David bought apples and pears at the grocery store for a fruit salad. At the
checkout counter, the apples weighed 2.7 pounds and the pears weighed 1.8
pounds. If the apples cost $1.29 per pound and the pears cost $1.49 per pound,
how much did David spend on fruit? (Round your answer to the nearest cent.)



 Apples:              Pears:
  1.29               1.49
  2.7               1.8                          3.483  2.682  6.165
   903               1192
 2580                1490                                   David spent $6.17
 3.483              2.682                                   on the fruit.



                                                                  Angel, Elementary Algebra for College Students, 6e, # 8
                          Tobey & Slater, Basic College Mathematics, 5e - Slide #8

								
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