Is this definition of a rectangle reversible? If yes, write it as a true biconditional.
A rectangle is a parallelogram with 4 right angles.

Now, martin can reasonably guess that the standard deviation for the entire population of people at the mall during the time of the survey is $1.50. what is the 95% confidence interval about the sample mean? interpret what this means in the context of the situation where 95 people were surveyed and the sample mean is $8. use the information in this resource to construct the confidence interval.

Ireally don't understand this, i'm really an idiot but i want to know how to figure this out. !

Brad earns $12.75/hr and works 40 hours a week. what is his gross annual income?