JEE Main 2020 · MathsMultiple choiceSingle correctMediumCalculation

JEE Main 9 January 2020, Shift 1, Maths Q68

Question 68 of 75 in this shift, Maths question 18 of 25, Section A.

Let the observations

x_i(1\le i\le 10)

satisfy the equations,

\sum_{i=1}^{10}(x_i-5)=10

and

\sum_{i=1}^{10}(x_i-5)^2=40

. If

\mu

and

\lambda

are the mean and the variance of the observations,

x_1-3, x_2-3, \ldots., x_{10}-3

, then the ordered pair

(\mu, \lambda)

is equal to :

(1) $(6, 6)$
(2) $(3, 6)$
(3) $(6, 3)$
(4) $(3, 3)$ Official answer

Official answer

Option 4

NTA final key (Jan 2020).

Chapter: Statistics
Topic: Variance and SD
Idea tested: Effect of Linear Transformations

Same idea in other shifts

Asked 4× in all

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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. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.