Activities

Solve for x 

4. Anna works at a clothing store and can fold 24 shirts in 8 minutes.  At that rate how many shirts can she fold in 40 minutes?
   
   
5. A jet travels 471 miles in three hours.  At this rate, how far could the jet fly in 16 hours?  What is the rate of speed for the jet?
   
   
6. A 10-pound bag of potatoes costs $4.50 at the grocery store.  Keith is making mashed potatoes for a large party and needs 25 pounds for the recipe.   At the given rate, how much will it cost to buy 25 pounds of potatoes?

7. A gallon of milk costs $3.20 and contains 16 servings.  What is the unit price of the milk per serving?  At this rate explain how much it would cost to buy enough gallons of milk to serve 500 students during a school lunch?
   
   
8. Julie wanted to earn some money so she could buy a new bike that costs $125.00.  Currently she has $45 saved in her bank account.  She started babysitting and earned $21 in 3 hours. At this rate how many hours will she have to work to save enough money to buy the new bike?  Show or explain your work.

Answer Key/Rubric

1. x = 32
   
   
2. x = 24
   
   
3. x = 5
   
   
4. 120 shirts.

The unit rate is 3 shirts per minute so in 40 minutes she can fold 120 shirts.  (3)(40) = 120

5. The jet could fly 2,512 miles in 16 hours.  The unit rate is 157 miles per hour.

6. $11.25

The unit rate is $0.45 per pound so the 25 pounds would cost $11.25. (0.45)(25) = 11.25

7. One cup serving of milk will cost $0.20. To serve 500 students it would cost $102.40.

        Acceptable explanations may include, but are not limited to:

• • Unit price of the milk is $3.20 divided by 16 servings = $0.20 per serving
  • Can’t just multiply $0.20 per serving times the number of students because milk must be sold by the gallon not by the serving.
  • You need to find the number of gallons of milk that you need to buy.  Each serves 16 servings so 500 ÷ 16 = 31.25. 
  • The number of gallons of milk that you need to buy must be rounded up to 32 because you can’t by part of a gallon of milk.
  • Total cost of milk is (3.20)(32) = $102.40

8. She will have to work 12 hours to have enough money for the new bike.

        Acceptable explanations may include, but are not limited to:

• • She needs to subtract the money that she has already saved from the amount that the bike costs. $125 - 45 = $80
  • The unit rate of what she is earning per hour is $7. To find that you have to divide the amount of money earned by the amount of hours she worked.  $21 ÷ 3 = $7.
  • To see how many hours she will need to work take the amount of money she needs to earn and divide by her hourly rate. $80 ÷ 7 = 11.42857….
  • Round the answer up to 12 hours since she gets paid by the hour