JEE Main 2022 · 27 Jul · Shift 1 · Mathematics Q22

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MathematicsInteger+4 / -1Question 22 of 90

The mean and variance of 10 observations were calculated as 15 and 15 respectively by a student who took by mistake 25 instead of 15 for one observation. Then, the correct standard deviation is ______.

Your answer

Answer and worked solution

Official answer: 2

Wrong totals. $\sum x=150$ , $\sum x^2=10(15+225)=2400$ .

Correct. $\sum x=140$ and $\sum x^2=2400-625+225=2000$ , so the variance is $200-196=4$ .

Answer: 2

Topics:Variance and standard deviation

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JEE Main 2022 · 27 Jul · Shift 1, Mathematics question 22