Math Answers

Find the t-value that bound in the middle of 80% with sample size 12

The time until a chemical reaction is complete (in milliseconds) has the density function f(x) = e^-x/100/100 for x ≥ 0.

a. Determine the mean and variance of x.

b. P(X>100).

There are 250 dogs at a dog show that weight an average of 12 pounds, with a standard deviation of 8 pounds .If 4 dogs are chosen at random, what is the probability that the average weight is greater then 8 pounds

Suppose f(x) = 3x^2/2 for - 1 < x < 1. Determine the mean and variance of X.

A population consists of the four numbers {2, 3, 6, 9}. Consider all possible samples of size 3 can be drawn without replacement from this population. Find the following:

a. mean of the population

b. population variance 

c. standard deviation of the population

d. mean of the sampling distribution of means

e. the standard deviation of the sampling distribution of means

f. List down all the possible samples of size 3.

g. construct a sampling distribution

The average preschool cost for tuition fees last year was 17,250. The following year, 20 institutions had a mean of 16,150 and a standard deviation of 2,250 is there sufficient evidence at =0.10 level of significance to conclude that the mean cost has increased?

Find the variance of the expected value of the probability distribution, X={1, 2, 3, 4, 5} P(X)={.10, .35, .15, .23, .17}

Two coins are tossed simultaneously. The outcome of the first coin is head. Let x be a random variable that denotes the number of heads that appear. What are the possible value of x?