/

Learn

Saturday, 10 October

/

JEE Main 2020 · MathsMultiple choiceSingle correctMediumMulti-step

JEE Main 2 September 2020, Shift 1, Maths Q67

Question 67 of 75 in this shift, Maths question 17 of 25.

Let

X=\{x\in\mathbf{N} : 1\le x\le 17\}

and

Y=\{ax+b : x\in X

and

a, b\in\mathbf{R}, a>0\}

. If mean and variance of elements of Y are 17 and 216 respectively then

a+b

is equal to :

(1) $-27$
(2)7
(3) $-7$ Official answer
(4)9

Official answer

Option 3

NTA final key (Sep 2020).

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

Same idea in other shifts

Asked 2× in all

8 Jan 2020, Shift 1 · Q67The mean and the standard deviation (s.d.) of 10 observations are 20 and 2 respectively. Each of these 10 observations is multiplied by p…MediumSingle correct

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 42 of the 174 JEE Main shifts held from 2017 to 2026.