Expert: Sherman D. - 9/14/2004

Question
What is the difference between precision and accuracy?Like in my book I did an example saying,"Three scientists measure the standard meter bar kept at the International Bureau of Standards. Their measurements are 1.09 m, 1.09 m, and 1.08 m. Are there measurements precise, accurate or both? Why?"When my teacher reviewed the example, he said its both, but I don't understnad how there can be an example that has an answer that's not both.Please explain the difference between accuracy and precision. Thank you so much. Have a great day.

Answer
Precision = Estimate
Accuracy = Exact

The reason why it is both

(1.09 + 1.09 + 1.08)/3 = 1.086666666

Since you have 3 significant figures, your problem must be rounded to 3 SIG FIGs, so the answer becomes 1.09 which is accurate because each value is 1.09, and it is 1.09 when rounded.

Precision would be to say that PI equals 3.14
Accurate would be to say that PI equals 3.14159265358979...

I believe that is how you would say the difference is.