JEE Main 2020MathematicsStatisticsMediumNumerical

JEE Main 2020 — Statistics Question with Solution

JEE Main 2020 (04 Sep Shift 2)

Question

If the variance of the following frequency distribution:

Class:         10-20        20-30        30-40
Frequency:   2                 x                         2
is 50, then x is equal to _______ 

Enter your answer

Show full solutionCorrect answer: 4
Correct answer
4

Step-by-step explanation

Given data can also be expressed as:

xi152535fi2x2

So,

x¯=∑fixiΣfi=30+25x+704+x=254+x4+x=25

Now, σ2=50=∑fixi2Σfi-x¯2

50=450+625x+24504+x-252

⇒50=2900+625x4+x-625

⇒675(4+x)=2900+625x

⇒50x=200⇒x=4

Practice this on the real CBT interface

Solve this JEE Main question (and the rest of the Statistics chapter) on PrepSharp's TCS iON-style CBT player — with timer, bookmarks and session analytics.

Solve interactively →

About this question

This is a previous-year question from JEE Main 2020, 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.