1. EXAMPLE 2 Solving a Problem Junior Iditarod Race In the 2001 Junior Iditarod race, one team completed the race in about 18 hours over two days. The team’s average rate was 8.325 miles per hour. About how long was the race? Round to the nearest mile.

2. EXAMPLE 2 Solving a Problem Use the formula Distance = Rate Time SOLUTION

3. EXAMPLE 2 Solving a Problem Use the formula Distance = Rate Time SOLUTION 8.325 18

4. EXAMPLE 2 Solving a Problem Use the formula Distance = Rate Time SOLUTION 8.325 18 66600 8325 149.850 Place the decimal point before dropping any zeroes

5. EXAMPLE 2 Solving a Problem Use the formula Distance = Rate Time SOLUTION 8.325 18 66600 8325 149.850 Place the decimal point before dropping any zeroes ANSWER The race was about 150 miles long.

6. EXAMPLE 3 Checking for Reasonableness Use estimation to check that the answer to Example 2 is reasonable.

7. EXAMPLE 3 Checking for Reasonableness Use estimation to check that the answer to Example 2 is reasonable. Distance = 8.325 18

8. EXAMPLE 3 Checking for Reasonableness Round 8.325 to its leading digit. Use estimation to check that the answer to Example 2 is reasonable. Distance = 8.325 18 8 18

9. EXAMPLE 3 Checking for Reasonableness Round 8.325 to its leading digit. Use estimation to check that the answer to Example 2 is reasonable. Distance = 8.325 18 8 18 = 144

10. EXAMPLE 3 Checking for Reasonableness Round 8.325 to its leading digit. Use estimation to check that the answer to Example 2 is reasonable. Distance = 8.325 18 8 18 = 144 ANSWER Because 150 is close to 144, the distance is reasonable.

11. GUIDED PRACTICE for Example 2 and 3 Find the product. 5. 0.9 50

12. GUIDED PRACTICE for Example 2 and 3 Find the product. 5. 0.9 50 = 45

13. GUIDED PRACTICE for Example 2 and 3 Find the product. 5. 0.9 50 = 45 6. 1.505 8

14. GUIDED PRACTICE for Example 2 and 3 Find the product. 5. 0.9 50 = 45 6. 1.505 8 = 12.04

15. GUIDED PRACTICE for Example 2 and 3 Find the product. 5. 0.9 50 = 45 6. 1.505 8 = 12.04 7. 3.14 75

16. GUIDED PRACTICE for Example 2 and 3 Find the product. 5. 0.9 50 = 45 6. 1.505 8 = 12.04 7. 3.14 75 = 235.5

17. GUIDED PRACTICE for Example 2 and 3 Bicycle Race You complete the first leg of a bike race in about 12 hours over two days. Your cyclometer shows that your average speed for this leg was 15.95 miles per hour. About how long was this leg of the race?

18. GUIDED PRACTICE for Example 2 and 3 Bicycle Race You complete the first leg of a bike race in about 12 hours over two days. Your cyclometer shows that your average speed for this leg was 15.95 miles per hour. About how long was this leg of the race? ANSWERAbout 192 miles

19. GUIDED PRACTICE for Example 2 and 3 Use estimation to check whether the answer is reasonable. 9. 3.254 18; 58.572

20. GUIDED PRACTICE for Example 2 and 3 Use estimation to check whether the answer is reasonable. 9. 3.254 18; 58.572 The answer is reasonable.

21. GUIDED PRACTICE for Example 2 and 3 Use estimation to check whether the answer is reasonable. 9. 3.254 18; 58.572 The answer is reasonable. 10. 12.706 3; 381.18

22. GUIDED PRACTICE for Example 2 and 3 Use estimation to check whether the answer is reasonable. 9. 3.254 18; 58.572 The answer is reasonable. 10. 12.706 3; 381.18 The answer is not reasonable.

23. GUIDED PRACTICE for Example 2 and 3 Use estimation to check whether the answer is reasonable. 9. 3.254 18; 58.572 The answer is reasonable. 10. 12.706 3; 381.18 The answer is not reasonable. 11. 15.312 4; 61.248

24. GUIDED PRACTICE for Example 2 and 3 Use estimation to check whether the answer is reasonable. 9. 3.254 18; 58.572 The answer is reasonable. 10. 12.706 3; 381.18 The answer is not reasonable. 11. 15.312 4; 61.248 The answer is reasonable.

25. GUIDED PRACTICE for Example 2 and 3 12. Explain why the answer 84 is not reasonable for the product 3 2.8.