Question

A student measures the time period of $100$ oscillations of a simple pendulum four times. The data set is $90s,91s,95s$ and $92s$. If the minimum division in the measuring clock is $1s$, then the reported mean time should be

• A. $92\pm 2s$
• B. $92\pm 5.0s$
• C. $92\pm 1.8s$
• D. $92\pm 3s$

Answer 1

The correct option is A $92\pm 2s$

Sum of all observation = $90+91+95+92=368$
Average $=368/4=92$

Sum of modulus errors = $2+1+3=6$
Average error $=6/4=1.5$, rounded off to $2$.
Final answer $=(92\pm 2)s$