JEE Main 2021 · MathsNumerical answerNumerical valueMediumCalculation

JEE Main 31 August 2021, Shift 1, Maths Q90

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

The mean of 10 numbers

7\times8,\ 10\times10,\ 13\times12,\ 16\times14,\ ...

is __________.

Official answer

398

NTA final key.

Chapter: Statistics
Topic: Variance and SD
Idea tested: Mean of Discrete Data

Same idea in other shifts

Asked 6× in all

2 Apr 2026, Shift 1 · Q8If the mean of the data | Class | 5-10 | 10-15 | 15-20 | 20-25 | 25-30 | 30-35 | | Frequency | 2 | $k$ | 28 | 54 | $k+1$ | 5 | is $21$ ,…MediumSingle correct
11 Apr 2023, Shift 1 · Q13Let $x_1, x_2, \ldots, x_{100}$ be in an arithmetic progression, with $x_1 = 2$ and their mean equal to 200. If…MediumSingle correct
22 Jul 2021, Shift 2 · Q89Consider the following frequency distribution : Class : 0 - 6 | 6 - 12 | 12 - 18 | 18 - 24 | 24 - 30 Frequency : a | b | 12 | 9 | 5 If…MediumNumerical value
18 Mar 2021, Shift 1 · Q87The mean age of 25 teachers in a school is 40 years. A teacher retires at the age of 60 years and a new teacher is appointed in his place.…EasyNumerical value
6 Sep 2020, Shift 2 · Q75Consider the data on $x$ taking the values $0, 2, 4, 8, \ldots, 2^n$ with frequencies ${}^nC_0, {}^nC_1, {}^nC_2, \ldots, {}^nC_n$ …MediumNumerical 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. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.