CAHSEE Math Problem of the Day -- Week 16

CAHSEE Math Problem of the Day -- Week 16Teacher Notes & AnswersWeek Week 16 – Day 3Concept/Skill Estimating divisionStandard 7 MR: 2.1 Use estimation to verify the reasonableness of calculatedresults.Materials CAHSEE Math Released Item # 143• Have students do the CAHSEE released test item on Day 3 of the student CAHSEEMath Problem of the Day -- Week 16 worksheet.Day 3 POD(CAHSEE Math Released Item # 143 )143. Sally paid $1.89 for 5 plums. About how many plums would she get for $10?A 4B 5C 10D 25Here is an example where students should begin by eliminating the obviously wronganswers.A is wrong because it is less than the number of plums Sally got for $1.89.B is wrong because it is the same as the number of plums Sally got for $1.89.That leaves C and D.Do an estimate: Sally paid about $2 for 5 plums so for $10 she should get 5 times as many plumsor 5 x 5 = 25. The correct answer is D.Laura Westermeier, Ed.D. Fall 2007SAUSD, Educational Services Week 16 – Teacher - Page 4 of 6

CAHSEE Math Problem of the Day -- Week 16Teacher Notes & AnswersWeek Week 16 – Day 4Concept/Skill Estimating percentStandard 7 MR: 2.1 Use estimation to verify the reasonableness of calculatedresults.Materials CAHSEE Math Released Item # 141• Have students do the guided practice test item on Day 4 of the student CAHSEEMath Problem of the Day -- Week 16 worksheet.Day 4 POD(CAHSEE Math Released Item # 142 )142. The temperature on a mountain peak was 7 degrees Fahrenheit (°F) at 6:00p.m. By 8:00 p.m., the temperature had dropped to 0°F. If the temperaturecontinued to drop at about the same rate, which is the BEST estimate of thetemperature at 11:00 p.m.?ABCD-20°F-14°F-10°F-9°FStart by drawing a number line to show the time and the drop in temperature:6:00 7:00 8:00 9:00 10:00 11:007 0 -3.5 -7 -10.5At 11:00 the temperature should be about -10.5 which is closest to C -10°FLaura Westermeier, Ed.D. Fall 2007SAUSD, Educational Services Week 16 – Teacher - Page 5 of 6

CAHSEE Math Problem of the Day -- Week 16Teacher Notes & AnswersWeek Week 16 – Day 5Concept/Skill Estimating rateStandard 7 MR: 2.1 Use estimation to verify the reasonableness of calculatedresults.Materials CAHSEE Math Released Item # 142Day 5• Have students do the CAHSEE released test item on Day 5 of the student CAHSEEMath Problem of the Day -- Week 16 worksheet.Day 5 POD(CAHSEE Math Released Item # 141 )141. Marcus plans to buy a CD that has a regular price of $13.99. It is on sale for10% off, but Marcus will have to pay 7% sales tax. Which is the MOSTreasonable estimate of the total cost of the CD including tax?A $12.50B $13.50C $14.50D $15.50First estimate that the price of the CD is $14.If it is 10% off then you need to subtract 14 -1.40 to get a cost of $12.60.You then need to add the tax so multiply the new cost of the CD (rounded to the nearest 1)13 x .07 to get a tax of .91 which is close to $1.00.To find the total cost add $12.60 and $1.00 to get $13.60 which is closest to B $13.50• At the end of the week remind students to keep the student CAHSEE MathProblem of the Day -- Week 1 worksheet to use as a study guide as they continueto prepare for the CAHSEE.Laura Westermeier, Ed.D. Fall 2007SAUSD, Educational Services Week 16 – Teacher - Page 6 of 6