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by zorro
Wed Jul 07, 2010 2:06 am
Forum: Statistics
Topic: Let X, Y, be ind. Poisson rand. vars; mean 1; find P(X+Y=4),
Replies: 7
Views: 9111

Re: Let X, Y, be ind. Poisson rand. vars; mean 1; find P(X+Y

I couldnt understand how to evaluate P(A+B=4) as is it P(A+B=4) = P(A) + P(B) = 4 or is it some other way If X is poisson 1 and Y is poisson 1 then X+Y is Poisson 2 but how should i represent it in my solution P(A+B) = 1+1 = 2 but what about the '4' I am having a hard time how to formulate this ? s...
by zorro
Tue Jul 06, 2010 2:53 am
Forum: Statistics
Topic: Need to know which formulae which has been used
Replies: 2
Views: 4951

Re: Need to know which formulae which has been used

If you're not sure what formula this is, try working backwards from the "sample" formulas they've given you. Which one uses in the numerator? Which one also uses in the denominator? :thumb:
Thanks!!
by zorro
Tue Jul 06, 2010 2:50 am
Forum: Statistics
Topic: Let X, Y, be ind. Poisson rand. vars; mean 1; find P(X+Y=4),
Replies: 7
Views: 9111

Re: Let X, Y, be ind. Poisson rand. vars; mean 1; find P(X+Y

Start with this... http://en.wikipedia.org/wiki/Poisson_distribution#Properties Thanks so \mu = \lambda = 1 P(A+B=4) = ? stuck here !!! From the link I provided look at "Sums of Poisson-distributed random variables" I couldnt understand how to evaluate P(A+B=4) as is it P(A+B=4) = P(A) + P(B) = 4 o...
by zorro
Mon Jul 05, 2010 4:04 pm
Forum: Statistics
Topic: Let X, Y, be ind. Poisson rand. vars; mean 1; find P(X+Y=4),
Replies: 7
Views: 9111

Re: Let X, Y, be ind. Poisson rand. vars; mean 1; find P(X+Y

Question :
Suppose X and Y are independent Poisson random variable , each with the mean 1 , obtain
i) P(X+Y=4)
ii) E[(X+Y)2]
Start with this...http://en.wikipedia.org/wiki/Poisson_di ... Properties
Thanks

so = = 1

P(A+B=4) = ? stuck here !!!
by zorro
Mon Jul 05, 2010 11:41 am
Forum: Statistics
Topic: Let X, Y, be ind. Poisson rand. vars; mean 1; find P(X+Y=4),
Replies: 7
Views: 9111

Let X, Y, be ind. Poisson rand. vars; mean 1; find P(X+Y=4),

Question :
Suppose X and Y are independent Poisson random variable , each with the mean 1 , obtain
i) P(X+Y=4)
ii) E[(X+Y)2]
by zorro
Mon Jul 05, 2010 3:44 am
Forum: Statistics
Topic: prob. of 3 red, 2 white, 1 blue (is the answer correct)
Replies: 5
Views: 5910

Re:

Assuming the decimal points stand for multiplication, could you please show the steps in your arithmetic with the fractions?
Sorry silly mistakes ....
P(R).P(R).P(R) + P(W).P(W) + P(B) = 0.4289
by zorro
Sun Jul 04, 2010 4:08 pm
Forum: Statistics
Topic: What is the probability that he really knows the answer
Replies: 4
Views: 5440

Re: What is the probability that he really knows the answer

then p(knows|correct)=p(correct|knows)*p(knows)/p(correct)
=1*1/2*1/(p(correct|knows)p(knows)+p(correct|guess)p(guess)+p(correct|copy)p(copy))
=.5*1/(p(knows)+p(guess)+1/48)
=24/41
That number seems a little low.
If u know the answer can u please let me know ?
by zorro
Sun Jul 04, 2010 4:03 pm
Forum: Statistics
Topic: random var. X is -1, 0, 1 w/ equal probability (check ans)
Replies: 4
Views: 5583

Re: random var. X is -1, 0, 1 w/ equal probability (check an

Please can u tell what is wrong


My work ........
E(X) = 0

1 = 0

2= 2/3

2 = 2/3

var(X) = 2 - 2 = 2/3 - 2/3 = 0

Thanks !!! :clap:
by zorro
Sun Jul 04, 2010 4:00 pm
Forum: Statistics
Topic: prob. of 3 red, 2 white, 1 blue (is the answer correct)
Replies: 5
Views: 5910

Re: prob. of 3 red, 2 white, 1 blue (is the answer correct)

12 is not a probability
Could u please help me solve this problem by pointing out the mistake
by zorro
Sun Jul 04, 2010 10:27 am
Forum: Statistics
Topic: prob. of 3 red, 2 white, 1 blue (is the answer correct)
Replies: 5
Views: 5910

prob. of 3 red, 2 white, 1 blue (is the answer correct)

Question : A box contains 5 red balls, 4 white balls and 3 blue balls . A ball is selected at random from the box . the colour of the ball is noted and then replaced back . Find the probability that out of 6 balls selected in this manner , 3 are red, 2 are white , 1 is blue. Solution : Let P(R) be t...

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