JEE Main 2022 · 26 Jun · Shift 1 · Mathematics Q18

← JEE Main 2022 · 26 Jun · Shift 1

MathematicsSingle correct+4 / -1Question 18 of 90

The mean of the numbers $a,b,8,5,10$ is 6 and their variance is 6.8. If M is the mean deviation of the numbers about the mean, then 25 M is equal to :

Answer and worked solution

Official answer: A

Mean. $a+b+23=30$ , so $a+b=7$ .

Variance. $\frac{a^2+b^2+189}5-36=6.8$ gives $a^2+b^2=25$ , so $\{a,b\}=\{3,4\}$ .

Mean deviation. $|3-6|+|4-6|+|8-6|+|5-6|+|10-6|=12$ , so $M=\frac{12}5$ and $25M=60$ .

(A)

Topics:Variance and standard deviation Measures of central tendency

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JEE Main 2022 · 26 Jun · Shift 1, Mathematics question 18