Problem: To the nearest thousandth, log102 is .301 and log103 is .477. Which of the following is the best approximation of log510?
Answer Choices:
A. 78
B. 79
C. 710
D. 711
E. 712
Solution:
Since logba=logab1,log510=log1051 =log1010−log1021≈.6991≈710. (The value of log103 was not used.)