College Algebra 9th txtbk

A-16 APPENDIX B SPECIAL TOPICS
So, in computing the length of the diagonal of the rectangular field shown earlier, we
write the answer rounded to three significant digits because the width has three significant
digits and the length has four significant digits:
d 246 meters
Three significant digits
One Final Note: In rounding a number that is exactly halfway between a larger and a smaller
number, we use the convention of making the final result even.
EXAMPLE 2 Rounding Numbers
Round each number to three significant digits.
(A) 43.0690 (B) 48.05 (C) 48.15 (D) 8.017 632 10 3
SOLUTIONS (A) 43.1
(B) 48.0 ⎫
⎬
(C) 48.2 ⎭
(D) 8.02 10 3
Use the convention of making the digit before the 5 even
if it is odd, or leaving it alone if it is even.
MATCHED PROBLEM 2
Round each number to three significant digits.
(A) 3.1495 (B) 0.004 135 (C) 32,450 (D) 4.314 764 09 10 12
ANSWERS TO MATCHED PROBLEMS
1. (A) 5,009 (B) 12,300 (C) 23.4000 (D) 0.00050 (E) 0.0012
2. (A) 3.15 (B) 0.004 14 (C) 32,400 (D) 4.31 10 12
B-1 Exercises
In Problems 1–12, underline the significant digits in each
number.
1. 123,005 2. 3,400,002 3. 20,040
4. 300,600 5. 6.0 6. 7.00
7. 80.000 8. 900.0000 9. 0.012
10. 0.0015 11. 0.000 960 12. 0.000 700
In Problems 13–22, round each number to three significant
digits.
13. 3.0780 14. 4.0240 15. 924,300
16. 643,820 17. 23.65 18. 23.75
19. 2.816 743 10 3
20. 56.114 10 4
21. 6.782 045 10 4
22. 5.248 102 10 3
In Problems 23 and 24, find the diagonal of the rectangle with the
indicated side measurements. Round answers to the number of
significant digits appropriate for the given measurements.
23. 25 feet by 20 feet
24. 2,900 yards by 1,570 yards