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JEE Main 2024 · MathsMultiple choiceSingle correctMediumCalculation

JEE Main 27 January 2024, Shift 1, Maths Q20

Question 20 of 90 in this shift, Maths question 20 of 30, Section A.

Let

a_1, a_2, \ldots a_{10}

be 10 observations such that

\sum_{k=1}^{10}a_k=50

and

\sum_{\forall k<j}a_k\cdot a_j=1100

. Then the standard deviation of

a_1, a_2, \ldots, a_{10}

is equal to :

(1) $5$
(2) $10$
(3) $\sqrt{5}$ Official answer
(4) $\sqrt{115}$

Official answer

Option 3

NTA final key.

Chapter: Statistics
Topic: Variance and SD
Idea tested: Variance Formula Calculation

Same idea in other shifts

Asked 2× in all

5 Apr 2024, Shift 2 · Q29Let the mean and the standard deviation of the probability distribution | X | $\alpha$ | 1 | 0 | $-3$ | |---|---|---|---|---| | P(X) |…MediumNumerical valueHas a figure

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.