The mean diameter of a thin brass rod is to be measured by Vernier callipers. Why 100 observations should be preferred over to measurements?

[prasanna]

Vernier Callipers suffers from least count error which can be an instrumental as well as a random error. To minimise this error, repeated observations are taken several times say 100 times so that mean value of these observations come closer to the actual or true value of the measured quantity.