Friday
May 6, 2016

# Homework Help: Chemistry (Check)

Posted by Bryan on Thursday, January 11, 2007 at 10:54pm.

Label each of the three following sentences that describe accuracy with an A. Label each sentence that describes precision with a P.

___P___5. Four of five repetitions of a measurement were named numerically identical, and the fifth varied from the others in value by less than 1%.

___A____6. Eight measurements were spread over a wide range.

___A____7. A single measurement is within 1% of the correct value.

I GUESS I would call the first one P but it depends, partly at least, on whether 1% is acceptable or not. Frankly, I don't think 1% is very good precision. (1% is 10 parts per thousand. I think of good as 1 part per thousand.) I am also troubled by the phrase "were named numerically equal". I don't know what that means.

For #6 I GUESS I would might call it accuracy although it really isn't because there is nothing to indicate how close these measurments were to the accepted value. Eight measurements spread over a wide range with nothing to indicate how far the average of these numbers are from the accepted value makes me think this is an example of VERY POOR precision.
7. I would choose accuracy.