JEE Main 2021 — Statistics Question with Solution
From: JEE Main 2021 (Online) 27th August Evening Shift
Question
An online exam is attempted by 50 candidates out of which 20 are boys. The average marks obtained by boys is 12 with a variance 2. The variance of marks obtained by 30 girls is also 2. The average marks of all 50 candidates is 15. If is the average marks of girls and 2 is the variance of marks of 50 candidates, then + 2 is equal to ________________.
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Show full solutionCorrect answer: 25
Correct answer
25
Step-by-step explanation
= 2 (variance of boys)
n1 = no. of boys
= 12
n2 = no. of girls
= 2
=
variance of combined series
2 = 8
+ 2 = 17 + 8 = 25
n1 = no. of boys
= 12
n2 = no. of girls
= 2
=
variance of combined series
2 = 8
+ 2 = 17 + 8 = 25
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This is a previous-year question from JEE Main 2021, covering the Statistics chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.