JEE Main 2019 Mathematics question
A student scores the following marks in five tests: 45, 54, 41, 57, 43. His score is not known for the sixth test. If the mean score is 48 in the six tests, then the standard deviation of the marks in six tests is:
Answer: (A)
Solution
Sixth score = 48; deviations −3, 6, −7, 9, −5, 0: variance = 200/6 = 100/3, SD = .