Question

Which of the following measurements is most precise ?

• A. $5.00 \,mm$
• B. $5.00 \,cm$
• C. $5.00 \,m$
• D. $5.00 \,km$

Answer 1

Answer: (A)

$5.00 \,mm$

Answer 2

Precision is the degree to which several measurements provide answers very close to each other. It is an indicator of the scatter in the data. The lesser the scatter, higher the precision. Let us first check the units. In all the options magnitude is same but units of measurement are different. As here $5.00 \,mm$ has the smallest unit. All given measurements are correct up to two decimal places. However, the absolute error in (a) is $0.01 \,mm$ which is least of all the four. So it is most precise.