Elementary Statistic Problem

[Zarff]

1. The population measures {2, 4, 6, 8} are recorded on a logbook. Suppose
two of them are randomly selected, find
a. the mean of the sampling distribution of the sample means.
b. the variance of the sampling distribution of the sample means.
c. the standard deviation of the sampling distribution of the sample means.

2. A random sample of 49 foreign tourists showed that they spend an average of
USD 23.45 per visit at the Zoo. The standard deviation of the sample was USD 2.80.
a. Find the best point estimate of the population mean.
b. Find the margin of error for a 90% confidence interval.
c. Find the 90% confidence interval of the population mean. Interpret the
results.

3. Assume that the weights of all packages of sweet potatoes are normally
distributed with the mean of 30 kg and a standard deviation of 0.2 kg. One
hundred packages of sweet potatoes are randomly selected.
a. Construct the 95% confidence interval of mean weight of the package of
sweet potatoes.
b. Construct the 99% confidence interval of mean weight of the package of
sweet potatoes.
c. Based on the answer in part (a) and (b), which of the interval is larger?
Briefly explain.

4.The average time jogging from different age groups spent doing exercise
each day is shown as:

Age groups Average
15-19
20-24
25-54
55-64
65+

Average jogging time (mins)
25
52
64
58
39

We select at random 50 people who aged between 15 and 19. Assume that
the standard deviation is 1.5 minutes. What is the probability that the mean
time spent on jogging each day is between 24.7 and 25.5 minutes?

[HallsofIvy]

Seriously? You just want someone to do your homework for you? Why? So you can avoid learning anything, fail the tests, then fail the course? That doesn't sound very bright! TRY to do these problems yourself, show us what you have tried. Then we will know what help you need in order to learn!