1) A student measures the time period of 100 oscillatons of a simple pendulum four times. The data set is the 90s, 91s, 92s and 95s. If the minimum division in the measuring clock is 1s, then the reported mean times should be A) $(92\pm2s)$ B) $(92\pm5s)$ C) $(92\pm1.8s)$ D) $(92\pm3s)$ Answer: Option AExplanation:True value= $\frac{90+91+95+92}{4}=92$ Mean abosulte error = $\frac{\mid92-90\mid+\mid92-91\mid+\mid92-95\mid+\mid92-92\mid}{4}$ = $\frac{2+1+3+0}{4}=1.5$ value $(92\pm1.5)$ Since. least count is 1s Value = $(92\pm2s)$
