Thread: Random sample from a population.

please please help me out for these question below. They are very important to me. As I am not good on Statistic and I don't have the model answers for them, I really want someone who can show me the answers about them. Therefore, I can check if i was doing the questions in the right way.

Thank you very much!!!

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Question 5---In a large population of N adults, let m be the number who are obese. The number N is known, but the number m is not known. A random sample of n people is chosen, where n is much smaller than N. Let X be the number of obese people in the sample.

(a) State the distribution of the random variable X. Hence write down the expectation and variance of X.
(b) Let Y = NX/n. Show that Y is an unbiased estimator of m.
(c) Find the standard deviation of Y .
(d) Suppose that N = 2, 000, 000 and n = 1, 000. To what accuracy should the estimate of m be reported?

(a) State the distribution of the random variable X. Hence write down the expectation and variance of X.

it is Binomial dist(n, )
Expectation =
Variance =

(b) Let Y = NX/n. Show that Y is an unbiased estimator of m.
i am not sure about this part of the question,
what is Y?
since it is random sampling we expect sample to have same characteristics as population

Originally Posted by rubic

(a) State the distribution of the random variable X. Hence write down the expectation and variance of X.

it is Binomial dist(n, )
Expectation =
Variance =

(b) Let Y = NX/n. Show that Y is an unbiased estimator of m.
i am not sure about this part of the question,
what is Y?
since it is random sampling we expect sample to have same characteristics as population

Thank you very much, you are great great!!!