Question

a group of students is donating blood during a blood drive. a student has 9/20 probability of having type 'o' blood and a 2/5 probability of having type 'A'.what is the probability that a student has type 'o' or type 'a' blood and why?

Answer 1

For the answer to the question above,
the answer is "The student can have only one blood type, so the actual events are mutually exclusive. "

The probabilities are not mutually exclusive. Based on the group 

P(Type O) = 9/20 = 45% or 0.45 
P(Type A) = 2/5 = 40% or 0.40 
P(Other) = 3/20 = 15% or 0.15
I hope my answer helped you. Feel free to ask more questions. Have a nice day!

Answer 2

Hello there.

A group of students is donating blood during a blood drive. a student has 9/20 probability of having type 'o' blood and a 2/5 probability of having type 'A'.what is the probability that a student has type 'o' or type 'a' blood and why?

The student can have only one blood type, so the actual events are mutually exclusive.