JEE Main 2023 · MathsNumerical answerNumerical valueMediumCalculation

JEE Main 6 April 2023, Shift 2, Maths Q29

Question 29 of 90 in this shift, Maths question 29 of 30, Section B.

If the mean and variance of the frequency distribution

x_i

: 2, 4, 6, 8, 10, 12, 14, 16

f_i

: 4, 4,

\alpha

, 15, 8,

\beta

, 4, 5 are 9 and 15.08 respectively, then the value of

\alpha^2+\beta^2-\alpha\beta

is ___________.

The figure, in words

Frequency table with x_i = 2,4,6,8,10,12,14,16 and f_i = 4,4,alpha,15,8,beta,4,5

Official answer

NTA final key.

Chapter: Statistics
Topic: Variance and SD
Idea tested: Finding Unknown Frequency via Variance

Same idea in other shifts

Asked 3× in all

13 Apr 2023, Shift 1 · Q29Let the mean of the data | $x$ | 1 | 3 | 5 | 7 | 9 | | Frequency ( $f$ ) | 4 | 24 | 28 | $\alpha$ | 8 | be 5. If $m$ and $\sigma^2$ are…MediumNumerical value
4 Sep 2020, Shift 2 · Q71If 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…EasyNumerical value

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.