JEE Main 2022 · 28 Jun · Shift 1 · Mathematics Q23

← JEE Main 2022 · 28 Jun · Shift 1

MathematicsInteger+4 / -1Question 23 of 90

The mean and standard deviation of 15 observations are found to be 8 and 3 respectively. On rechecking it was found that, in the observations, 20 was misread as 5. Then, the correct variance is equal to ______.

Your answer

Answer and worked solution

Official answer: 17

Corrected sums. $\sum x=120+15=135$ , mean 9. $\sum x^2=15(9+64)-25+400=1470$ .

Variance. $\frac{1470}{15}-81=17$ .

Answer: 17

Topics:Variance and standard deviation

← Previous question Next question →

JEE Main 2022 · 28 Jun · Shift 1, Mathematics question 23