# Precision and Accuracy

## Homework Statement

Two different scientists measured the speed of light four times.

Scientist A
3.80*108m/s
3.32*108m/s
3.10*108m/s
3.05*108m/s
Average 3.32*108m/s

Scientist B
2.90*108m/s
3.10*108m/s
3.24*108m/s
2.95*108m/s
Average 3.05*108m/s

Accepted value of speed of light =3.00*108m/s

Vocabulary terms
The closer the values of a measurement are to each other, the greater the precision.
Accuracy is how close the values accepted value

2. The attempt at a solution

Scientist B has greater accuracy because the average of scientist B is closer to the accepted value.

Scientist A has greater precision because the numbers are close to each other than scientist B.

I'm not sure if scientist A has greater precision. The first measurement for scientist A 3.80*108m/s is not close in value to the other measurements. But the rest of the values for scientist A seem to be closer.

Ygggdrasil
Gold Member
2021 Award
I'd agree with you that scientist B has both greater accuracy and greater precision.

There is a commonly used statistic that scientists use to measure the precision of their measurements. Calculating that statistic for both scientists' datasets should make it clear which data set shows more precise measurements.

bobob
Gold Member
The most accurate measurement is the one closest to the "true" value, or in this case, accepted value. The most precise measurement is the one with the smallest error in the measurement.