Compare your answers.

  1. Which is the better buy? Show all work.
    2.  
    1. 12 cans of pop for $6.99 or
      32 cans of pop for $14.99



      The better buy is the 32 cans of pop, since the unit price for 32 cans is $0.47/can.

       
    2. 4.4 pounds of sugar for $4.99 or
      10 pounds of sugar for $9.25



      The better buy is the 10 pounds of sugar, since the unit price for 10 pounds is $0.93/pound.
       

  2. Grant wants to make meatballs for his pasta supper. He needs to defrost 1.56 kg of ground beef. If it takes 12 minutes to defrost 2 lbs of meat, how long will it take for Grant's 1.56 kg of ground beef to defrost?
    1 kg = 2.2 lb

    Convert kg to pounds



    Find the time to defrost 3.432 lb of ground beef.



    It will take 20.6 minutes to defrost 3.432 lbs of ground beef.


  3. A professional cyclist races at an average speed of 40 km/h and burns 2500 calories per hour in a 4-hour race. If an amateur cyclist races at an average of 30 km/h and burns over 7000 calories in a 4-hour race, how many more minutes must the amateur ride at his race pace to burn the same number of calories as the professional in his 4-hour race?

    Professional 40 km/h 2500 cal/h
    Amateur 30 km/h 7000 cal/4h

    The actual speeds of the cyclists do not factor into this particular problem.

    Step 1: Find the unit rate (number of calories per hour) for the amateur cyclist burning 7000 calories in 4 hours.



    Step 2: Determine the difference between the numbers of calories burned by each athlete in one hour.

    2500 - 1750 = 750

    The amateur burns 750 fewer calories per hour than the professional.

    In four hours, the amateur will burn 750 × 4 = 3000 fewer calories.

    Step 3: Determine how long it will take the amateur to burn 3000 calories.



    The amateur will need to ride an additional 1.71 hours to burn the same number of calories as the professional in his 4-hour race.

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