Hello, loutja35!

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Blood Types:

The probability that a person in the United States has type AB+ blood is 3%.

Five unrelated people in the United States are selected at random.

We have: .$\displaystyle \begin{Bmatrix}P(\text{AB+}) \:=\:0.03 \\ P(\text{Not}) \:=\:0.97 \end{Bmatrix}$

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a) Find the probability that all five have AB+ blood.

$\displaystyle P(\text{5 AB+}) \:=\:(0.03)^5 \:=\:0.0000000243$

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b) Find the probability that none of the five has type AB+ blood.

$\displaystyle P(\text{5 Not}) \:=\:(0.97)^5 \:=\: 0.8587340267$

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c) Find the probability that at least one of the five has type AB+ blood.

This is the *exact opposite* of part (b).

$\displaystyle P(\text{at least one AB+}) \;=\; 1 - 0.85873402578 \;=\;0.1412650743$