When we want to test a claim about two population means, most of the time we do not know the population standard deviations, and we assume they are no

The manager of the store in the preceding exercise calculated the residual for each point in the scatterplot and made a dotplot of the residuals.
The distribution of residuals is roughly Normal with a mean of $0 and standard deviation of $22.92.
The middle 95% of residuals should be between which two values? Use this information to give an interval of plausible values for the weekly sales revenue if 5 linear feet are allocated to the stores

Describe in words the surface whose equation is given. (assume that r is not negative.) $\theta =\frac{\pi }{4}$
a) The plane $y=-z$ where y is not negative
b) The plane $y=z$ where y and z are not negative
c) The plane $y=x$ where x and y are not negative
d) The plane $y=-x$ where y is not negative
e) The plane $x=z$ where x and y are not negative

Explain why t distributions tend to be flatter and more spread out than the normal distribution.

A pair of dice is rolled three times. What are the odds of five-total rolling each time?

9. The purpose of statistical inference is to provide information about the.
a. sample based upon information contained in the population.
b. population based upon information contained in the sample.
c. population based upon information contained in the population.
d. mean of the sample based upon the mean of the population.
10. Random samples of size 81 are taken from an infinite population whose mean and standard deviation are 200 and 18, respectively. The distribution of the population is unknown. The mean and the standard error of the mean are.
a. 200 and 18.
b. 81 and 18.
c. 9 and 2.
d. 200 and 2.

What is the number called that determines each unique T distribution?

Two normally distributed variables have the same means and the same standard deviations. What can say about their distributions?