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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 marks in six tests is
- 10/√3
- 100/3
- 100/√3
- 10/3
Correct answer: 10/√3
Solution
To find the standard deviation, we first need the mean of all six tests, which is given as 48. By calculating the total score needed for six tests (6 * 48 = 288) and subtracting the sum of the known scores (45 + 54 + 41 + 57 + 43 = 240), we find the sixth score must be 48. The standard deviation is then derived from the variance of these six scores, leading to the correct option of 10/√3.
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