# Tutor profile: Omar G.

## Questions

### Subject: Chemistry

The ionic radii of N^3-, O^2-, F^-, and Na^+ goes in which order from largest to smallest?

N^3- > O^2- > F^- > Na+ It is important to remember that ions (specifically anions) with negative charges have extra electrons that make them larger in an isoelectric series like the one in the question. A 3- charge means 3 extra electrons were gained so N^3- is the largest ion of this isoelectric series.

### Subject: Statistics

What are the differences that set apart independence from mutual exclusion?

Mutual exclusion is when two results are impossible to happen at the same time. Independence is when the probability of an event does not depend on the results that we have had previously. When written out in statistical terms it should look like this: p(A intersection B) = p(A)p(B | A) --> knowing A does not give any information about the next event say that p(B | A) = 0 so then p(A intersection B) = 0 P(A intersection B) = p(A)p(B)

### Subject: Microeconomics

What are the definitions of price elasticity, cross-price elasticity, and income elasticity? What do these mean in words?

Prices elasticity of demand is equal to the rate of change of the demand of a good divided by the rate of change in the price of a good. The income elasticity is the rate of change of the demand of a good divided by the rate of change of the income of an individual. The cross-price elasticity is equal to the rate of change of the demand for a good divided by the rate of change of the price of a second good. All of these definitions are all referring to changes in the demand of a good and the effect that it has on the change in another variable like income and price. The higher the value is the more sensitive demand is to changes in the other variable.

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