The least count of a stop watch is 0.1s. The time of 20 oscillations of the pendulum is found to be 20s. The percentage error in the time period is

Q. The least count of a stop watch is 0.1s. The time of 20 oscillations of the pendulum is found to be 20s. The percentage error in the time period is

1. 0.25%
2. 0.75%
3. 0.50%
4. 1.0%

Answer: 0.50%