6.2+Using+Rules+of+Thumb+1011

Z.D.    January 24, 2011     Math 7B A) **//It takes about 100 maple trees to make 25 gallons of maple syrup.// Mr. Paulo made maple syrup from all of his sugar maple trees. He ended up with 16 gallons of syrup. About how may sugar maple trees does he need? **

ans: 25 gallons = 100 trees        1 gallon = __100__         25 = 4 trees         16 gallons = 4 x 16 = 64 maple trees. B) **//A 5 minute shower requires about 18 gallons of water//. About how much water do you use for an 8 minute shower? How much water will you use if you take an 8 minute shower every day of the year?**          ans: 5 minutes = 18 gallons         1 minute = __18__         5 = 3         8 minute = __18__         5 x 8 = 28.8 gallons         28.8 x 365 = 10512 gallons a year          C) **//A double spaced page of text contains about 250 words if it is printed in Times with a font size of 12, and about 330 words if it is printed in Times with the font size of 10.// Jeremy printed his term paper in the computer lab. He used 10 - point Times and the paper came to 15 double spaced pages. Jeremy's teacher requires term papers be 20 double spaced pages long. If Jeremy changes the font to the 12 - point Times, how long will his paper be?** ans: 10 points - 15 double spaced        1 - point __15 3__         10 = 2         12 - points 15         10 x 12 = 18 double spaced D) **//Jogging// burns 100 per mile. Elizabeth jogs at a rate of 4.5 miles per hour. How long will it take her to burn 1200 - calorie lunch she ate at Burger Heaven?**           ans: 1 mile - 100 calories         4.5 - 100 x 4.5 = 450         450 - __4.5__         450         1200 - __4.5__         450x 1200 = 12 miles          6.2 Follow Up       **   Ask adults you know if they use rules of thumb in their jobs or at home. Write down one of the rules you learn. Write a problem that can be solved using the rule.   **       ans: Since 2 quarts are 4 pints of milk. Then how many is 1 quart?          2 quarts - 4 pint         1 quarts - 4         2 = 2