As in, if you have a population X∼D and you take samples X1,X2,⋯,Xn∼D then the variance of the samples are fundamentally distinct from the mean of the samples. I'm unsure as to what you mean by 'combine'? When calculating the mean of the samples, you don't concern yourself with the variance and likewise the other way around.
As in, if you have a population X∼D and you take samples X1,X2,⋯,Xn∼D then the variance of the samples are fundamentally distinct from the mean of the samples. I'm unsure as to what you mean by 'combine'? When calculating the mean of the samples, you don't concern yourself with the variance and likewise the other way around.
If the population had a mean of m and a variance of n. A sample of 50 is taken, how do I find the P(sample>t)?
Population is not normal right?
I edited my answer, sorry. You don't. You can't talk about it in stuff like that generally. Sums of two random variables with distributions of D don't necessarily have to have a D distribution.
I edited my answer, sorry. You don't. You can't talk about it in stuff like that generally. Sums of two random variables with distributions of D don't necessarily have to have a D distribution.
I am probably asking wrong. I'll make a question.
An average ticket for a game of poker is $2 with a standard deviation of $0.7. You want to play 100 games and have $220 to spend on tickets (can't spend winnings). What's the probability that you will run out?
A average ticket for a game of poker is $2 with a standard deviation of $1. You are going to play 100 games and have $220 to spend on tickets (can't spend winnings). What's the probability that you will run out?
How would I do this?
The expected value will be $200 and the standard deviation will be $10. Then, I think you'll need to invoke the CLT and assume it's approximately normally distributed to complete the question.
The expected value will be $200 and the standard deviation will be $10. Then, I think you'll need to invoke the CLT and assume it's approximately normally distributed to complete the question.
So will the new thing be T~N(200,100)?
How can you just combine the random variables if you don't know how they are distributed?
I modified my second question to your answer of my modified question.
E(X1+X2+⋯+Xn)=E(X1)+E(X2)+⋯+E(Xn) holds for any random variable, doesn't depend on its distribution at all. Proof involves some wacky marginal stuff. Same for the variance (although variance depends on independence).
E(X1+X2+⋯+Xn)=E(X1)+E(X2)+⋯+E(Xn) holds for any random variable, doesn't depend on its distribution at all. Proof involves some wacky marginal stuff. Same for the variance (although variance depends on independence).
Okay now I am more confused, how did you get 7? 0.7*100=70/games = 0.7
Okay now I am more confused, how did you get 7? 0.7*100=70/games = 0.7
You said the standard deviation was 0.7, so the variance is 0.49. Adding up the variances gives 0.49 * 100 = 49 is the variance. So standard deviation is sqrt(49) = 7.
You said the standard deviation was 0.7, so the variance is 0.49. Adding up the variances gives 0.49 * 100 = 49 is the variance. So standard deviation is sqrt(49) = 7.
Oh right that's how its done if we knew the mean/variance of our games but we have sampling here.
You said the standard deviation was 0.7, so the variance is 0.49. Adding up the variances gives 0.49 * 100 = 49 is the variance. So standard deviation is sqrt(49) = 7.
The question was
An average ticket for a game of poker is $2 with a standard deviation of $0.7. You want to play 100 games and have $220 to spend on tickets (can't spend winnings). What's the probability that you will run out?
The average of all games is $2, not the average of your games.