Question 23 - CBSE Class 12 Sample Paper for 2018 Boards - Solutions of Sample Papers and Past Year Papers - for Class 12 Boards
Last updated at Sept. 14, 2018 by Teachoo
Four bad oranges are accidentally mixed with 16 good ones. Find the probability distribution of the number of bad oranges when two oranges are drawn at random from this lot. Find the mean and variance of the distribution.
This is a question of CBSE Sample Paper - Class 12 - 2017/18.
Let
X : be the number of bad oranges
x 0 1 2 The Mean is given by :
E( )" =" 2_( =1)^
= 0 60/95+1 32/95+2 3/95
= 38/95
= 2/5
= 0.4
Hence the mean is 0.4
The variance of x is given by :
Var ( )= ( ^2 ) [ ( )]^2
So, finding ( ^2 )
E( ^ )= 2_( = 1)^ _ ^2
= 0^2 60/95+1^2 32/95+2^2 3/95
= 0 + 32/95 + 4 3/95
= 44/95
Now,
Var ( )= ( ^ ) [ ( )]^
= 44/95 (2/5)^2
= 44/95 4/25
= 44/(19 5) 4/(5 5)
= (44(5) 4 19)/(19 5 5)
= (220 76)/475
= /
Made by
Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths and Science at Teachoo.
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