Problem 1198

Use the information in this table to find the indicated probability.

  Blood Type
A B AB O Total
Rh Factor Positive 264 63 25 277 629
Negative 47 11 4 49 111
Total 311 74 29 326 740


What is the probability of selecting a donor that is blood type A or is Rh-positive?  Express the answer as a decimal rounded to the nearest thousandth.




The events are NOT mutually exclusive, so the probability is found by adding the individual probabilities and subtracting the common probability.


\frac{311}{740}+\frac{629}{740}-\frac{264}{740} = \frac{676}{740}\approx 0.914


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