Question

Students were asked to measure a string as part of a physics experiment. The actual length of the string was 7.35 cm long. Which of the following groups of data show measurements from the most accurate group and why?

7.35 cm, 7.82 cm, 7.12 cm, because one of the measurements is closest to the actual length.
6.95 cm, 6.93 cm, 6.97 cm, because these have the most agreement between the measurements.
7.32 cm, 7.37 cm, 7.39 cm, because this group’s measurements are closest to the actual length. - My answer
7.90 cm, 7.91 cm, 7.89 cm, because these have the most agreement between the measurements.

Answer 1

We can calculate the average for each data set to check the closest group to the actual measurement

Data set 1: 
Mean= (7.35+7.82+7.12) ÷ 3 = 7.43

Data set 2:
Mean = (6.95+6.93+6.97) ÷ 3 = 6.95

Data set 3:
Mean =  (7.32+7.37+7.39) ÷ 3 = 7.36

Data set 4:
Mean = (7.90+7.91+7.89) ÷ 3 = 7.9

From our calculation, the closest mean value to the actual length is data set 3, hence the data set 7.32, 7.37, 7.39 is the most accurate group