JEE Main 2020 — Statistics Question with Solution
From: JEE Main 2020 (Online) 8th January Evening Slot
Question
The mean and variance of 20 observations are
found to be 10 and 4, respectively. On
rechecking, it was found that an observation 9
was incorrect and the correct observation was
11. Then the correct variance is
Choose an option
Show full solutionCorrect option: B
Correct answer
B3.99
Step-by-step explanation
Let 20 observation be x1
, x2
,....., x20
Mean =
x1 + x2 +, .....+ x20 = 200
Variance =
4 = - 102
= 2080
Also x1 + x2 +, .....+ x20 - 9 + 11 = 202
new variance will be
= -
= 3.99
Mean =
x1
+ x2
+, .....+ x20
20
= 10
x1 + x2 +, .....+ x20 = 200
Variance =
4 = - 102
= 2080
Also x1 + x2 +, .....+ x20 - 9 + 11 = 202
new variance will be
= -
= 3.99
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This is a previous-year question from JEE Main 2020, covering the Statistics chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.