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Saturday, 31 October

JEE Main · Maths · Statistics

Finding Number of Observations from Variance

JEE Main asked Finding Number of Observations from Variance once in the 108 shifts Lumi analysed, on 2 Apr 2026, Shift 2. It belongs to Variance and SD, in Statistics (Maths).

Updated 2026-10-24

Times asked
1
in 1 shift
Years
1 of 8
First asked
2026
the only year
Pattern
New since 2024
asked once so far

Questions on this idea a shift, by year

2017–2026. Asked in 2026. Years differ in how many shifts Lumi analysed, so each year is scaled to one shift of 25 Maths questions.

00.10.20’170’200’210’220’230’240’250.11’26

Raw count: 2017: 0 in 1 shift · 2020: 0 in 12 shifts · 2021: 0 in 24 shifts · 2022: 0 in 24 shifts · 2023: 0 in 12 shifts · 2024: 0 in 18 shifts · 2025: 0 in 8 shifts · 2026: 1 in 9 shifts.

Shift by shift

Each square is one analysed shift, in date order. Open a filled one for that paper.

  • 20261 of 9
  • 20250 of 8
  • 20240 of 18
  • 20230 of 12
  • 20220 of 24
  • 20210 of 24
  • 20200 of 12
  • 20170 of 1

Asked in that shift More than once Not asked

How JEE Main framed it

Single correct is the usual form. Skill tested: calculation.

  • Find n from mean and variance

Difficulty

Easy 1Medium 0Hard 0

The question was multiple choice.

Every question

The question

From the official JEE Main shift papers, newest first. Open one for the full question, the options and the official answer.

  1. 2 Apr 2026, Shift 2 · Q9The mean and variance of nn observations are 8 and 16, respectively. If the sum of the first (n−1)(n - 1) observations is 48 and the sum of…EasySingle correct

Shift: 2 Apr 2026, Shift 2.

Same topic

Other ideas in Variance and SD

Variance and SD has 20 ideas JEE Main has asked; 10 of them came up in more than one question. The 12 most asked are below.

Topic analysisChapter analysisStudy this chapterAll repeated ideas