PLEASE HELP ME UNDERSTAND: What formulas do I use? and how do I know when do use them?

Find the indicated probability.

1) All human blood can be "ABO" typed as belonging to one of A, B, O, or AB types. The actual distribution varies slightly among different groups of people, but for a randomly chosen person from North America, the following are the approximate probabilities:

Blood Type

O

A

B

AB

Probability

0.45

0.40

0.11

?

What is the probability that a randomly chosen person from North America has AB type blood?

2)

Find the indicated probability.

In general,the probability that a blood donor has Type A blood is 0.40.

Consider 8 randomly chosen blood donors, what is the probability thatmore thanhalf of them have Type A blood?

3)

Find theindicated probability.

IQ scores are known to be normally distributed with a mean of 100 and a standard deviation of 15.

What is the probability that a randomly selectedindividualhas an IQ score that is less than 120?

4)

Find the indicated probability.

An insurance company has determined that the cost of a certain medical procedure varies according to a normal distribution with a mean of $800 and a standard deviation of $40.

If a new insurance claim comes in for this particular medical procedure, what is the probability the claim will be greater than $900?

5)

Identify the data value corresponding tothe indicated percentile.

The amount of sleep an adult gets per day is normally distributed with a mean of 7 hours and a standard deviation of 1.5 hours.

Five-percent of adults sleep more than how many hours per day?

6)

Find theindicated probability.

The age of professors at a certain university is normally distributed with an average of 45.0 years and a standard deviation of 6.0 years.

If 16 professors are chosen at random for a committee, find the probability that theaverageage of those professors is less than 42.0 years.

7)

Find theindicated probability.

The age of professors at a certain university is normally distributed with an average of 45.0 years and a standard deviation of 6.0 years.

If 16 professors are chosen at random for a committee, find the probability that theaverageage of those professors is greater than 42.0 years.

This is a practice test, I do not intend to submit this work as my own. I just need the concepts explained to me! Thank you.