A student uses a simple pendulum of exactly `1m` length to determine `g`, the acceleration due ti gravity. He uses a stop watch with the least count of `1sec` for this and record `40 seconds` for `20` oscillations for this observation, which of the following statement `(s) is (are)` true?

Options

A. Error `DeltaT` in measuring T, the time period, is 0.05 seconds
B. Error `DeltaT` in measuring T, the time period, is 1 second
C. Percentage error in the determination of g is 5%
D. Percentage error in the determination of g is 2.5%

Answer

A, C