Auniversity surveyed recent graduates of the english department for their starting salaries. four hundred graduates returned the survey. the average salary was $25,000, with a standard deviation of $2,500. what is the best point estimate of the population mean?

Step-by-step explanation:

Data given

represent the sample mean obtained

represent the sample deviation obtained

represent the true mean (variable of interest)

n=400 represent the sample size selected

Solution to the problem

The best estimator for the true mean is given by the sample mean , and the reason is: If we assume that in tha random sample each observation follows a normal distribution like this:

Then when we find the expected value for the sample mean we have this:

If we use the properties of the expected value we have:

And since the expected value of each observation is the same we have:

So then we have that the best estimator for the population mean is given by:

the answer   is 200

step-by-step explanation:

this is a problem about poisson probabilities.   i don't know if you've

already studied poisson distributions, or if you have a place to look

to read more about the subject.  

here's how you can see a poisson distribution coming.   when there are

a lot of events that may happen at any time (or any place), and when

you're counting how many of them happen at a particular time (or a

particular place), and each event is independent of the others, then

the result is a poisson distribution.   this is roughly true for the

chocolate chips; one chip being in a cookie has only a small effect on

the probability that another chip will be in the cookie.

once you know you have a poisson distribution, you know a lot.   there

is only one parameter to a poisson distribution, so if you know the

mean, you know everything.   the form of the distribution is

  probability of n chips = {[e^(-x)]*(x^n)} / (n! )

x = 25/2304

step-by-step explanation: