JEE Main 2019MathematicsStatisticsMediumMCQ

JEE Main 2019 — Statistics Question with Solution

JEE Main 2019 (10 Apr Shift 1)

Question

If for some x∈R, the frequency distribution of the marks obtained by 20 students in a test is:

Marks 2 3 5 7
Frequency distribution x+12 2x-5 x2-3x x

Then the mean of the marks is :

Choose an option

Show full solutionCorrect option: D
Correct answer
D2.8

Step-by-step explanation

Total students =20

⇒  x+12+2x-5+x2-3x+x=20

⇒   x2+2x+1+2x-5+x2-3x+x=20

⇒   2x2+2x-24=0  ⇒  x2+x-12=0

⇒    x=-4, 3    ∵  x>0

∴    x=3

Average =x+12×2+2x-53+5x2-3x+7×x20

=32+3+0+2120=2.8

Hence, required mean is 2.8

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About this question

This is a previous-year question from JEE Main 2019, 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.