Three measurements of the time for 20 oscillations of a pendulam give t_1=39.6s,t_2=39.9and t_3=39.5s. What is the precision in the measurements? What is the accuracy of the measurements?

Three measurements of the time for 20 oscillations of a pendulam give

1.	Three measurements of the time for 20 oscillations of a pendulam give t_1=39.6s,t_2=39.9and t_3=39.5s. What is the precision in the measurements? What is the accuracy of the measurements?
Answer» SOLUTION :Precision is the least measurable value with that instrument in our case precision is `pm 0.1 sec`. Calculate of accuracy: Average value of measurements `=(39.6+39.9+39.5)/3=119/3=39.67` Error in each measurement = `Deltaa_1=39.67-39.6=0.07`, `Deltaa_2=39.9-39.67=0.23,` `Deltaa_3=39.67-39.5 =0.17` `Deltaa_(mean)=(0.07+0.23+0.17)/3=0.156` Precision `pm 1 sec`. In these measurements only two siginificant figures are believable. 3rd One is uncertain. Adjustment of `Deltaa_(mean)` upto given SIGNIFICANT FIGURE =0.156 adjusted to 0.2. So our value is accurate upto `pm0.2` So our result is 39.67 `pm` 0.2, when significant figures taken into ACCOUNT it is 39.7 `pm0.2 sec.