Question

Three measurements $7.1J,7.2Jand6.7J$ were made as experiment. The result with correct number of significant figures is

• A. $7.06J$
• B. $7.0J$
• C. $7J$
• D. $7.1J$

Answer 1

The correct option is B $7.0J$

Added result $R=7.1+7.2+6.7=21$ .
All the three measurements have 2 significant figures, thus the added result must also have 2 significant figures.
Number of observations is $3$.
Thus averaged result $Ravg=\frac{21}{3}=7.0J$