Use Ming and Keenya's table to answer Questions 20–22. Write a number sentence showing how you found each estimate.

  1. Estimate the number of acres of national park land in Colorado.
  2. Which state, Arizona or Colorado, has more national park land? Estimate the difference.
  3. Mammoth Cave is the longest known cave network in the world. Estimate the difference in size between Mammoth Cave National Park and Wind Cave National Park.

Raising Money

The Parent-Teacher Club at Bessie Coleman School wants to purchase computers for the school over a two-year period. The club's goal is to purchase computer equipment for 25 stations. Club members made a table to show what they wanted to buy:

Check-In: Question 23

  1. Use estimation to set a goal for the amount of money the Parent-Teacher Club needs to earn. Write a paragraph explaining how you arrived at your estimate. Use the Math Practices page in the Reference section to help you write your paragraph.