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CBSE Class 12-science Answered

there are 4 cards numbered 1 to 4 one number on one card . 2 cards are drawn at random without replacement . let x denote the sum of numbers on the 2 drawn cards . find the mean and varience of x  
Asked by alanpeter9611 | 12 Feb, 2019, 05:18: PM
answered-by-expert Expert Answer
f o l l o w i n g space s u m s space a r e space p o s s i b l e space 3 comma 4 comma 5 comma 6 comma 7 table row straight x 3 4 5 6 7 row cell straight P left parenthesis straight x right parenthesis end cell cell 2 over 12 end cell cell 2 over 12 end cell cell 4 over 12 end cell cell 2 over 12 end cell cell 2 over 12 end cell end table table row cell straight x. straight P left parenthesis straight x right parenthesis end cell cell 3 over 6 end cell cell 4 over 6 end cell cell 5 over 3 end cell cell 6 over 6 end cell cell 7 over 6 end cell row cell straight x squared. straight P left parenthesis straight x right parenthesis end cell cell 9 over 6 end cell cell 16 over 6 end cell cell 25 over 3 end cell cell 36 over 6 end cell cell 49 over 6 end cell end table m e a n equals begin inline style sum for blank of end style straight x. straight P left parenthesis straight x right parenthesis equals 30 over 6 equals 5 v a r i a n c e equals begin inline style stack sum straight x squared. straight P left parenthesis straight x right parenthesis with blank below end style minus begin inline style open parentheses sum for blank of straight x. straight P left parenthesis straight x right parenthesis close parentheses end style squared equals 160 over 6 minus 25 equals 5 over 3
Answered by Arun | 13 Feb, 2019, 11:01: AM

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CBSE 12-science - Maths
there are 4 cards numbered 1 to 4 one number on one card . 2 cards are drawn at random without replacement . let x denote the sum of numbers on the 2 drawn cards . find the mean and varience of x  
Asked by alanpeter9611 | 12 Feb, 2019, 05:18: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 12-science - Maths
Four bad eggs are mixed with 10 good ones . three eggs are drawn one by one without replacement. Let X be the no of bad eggs  drawn . Find the mean and variance of X.  
Asked by haroonrashidgkp | 07 Nov, 2018, 09:14: PM
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CBSE 12-science - Maths
A box contains 16 bulbs , out of which 4 bulbs are defective. Three bulbs are drawn at random from the box. Let X be the no of defective bulbs drawn . find the mean and variance of X
Asked by haroonrashidgkp | 05 Nov, 2018, 09:42: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 12-science - Maths
What is the mean of a random variable
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
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CBSE 12-science - Maths
Define variance and standard deviation of a random variable.
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
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CBSE 12-science - Maths
Find the mean of the number obtained on a throw of an unbiased dice
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
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CBSE 12-science - Maths
Two dice are thrown simultaneously. If X denotes the number of sixes, find the variance of X.
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
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CBSE 12-science - Maths
In a meeting, 70% of the members favour and 30% oppose a certain proposal. A member is selected at random and we take X = 0 if he opposed, and X = 1 if he is in favour. Find E(X) and Var(X).
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
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CBSE 12-science - Maths
Let a pair of dice be thrown and the random variable X be the sum of the numbers that appear on the two dice. Find the mean or expectation of X.
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
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CBSE 12-science - Maths
A bag contains 4 black and 3 red balls. Let X be the random variable of red balls. Find the mean and variance of the random variable X, if three balls drawn successfully with replacement.
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
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