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About 26% of orthopedic surgeries involves knee problems. The following table summarizes data collected from a sample of adults who have knee surgery. (Source:

American Academy of Orthopedic Surgeons).

Age Full Knee Replacement No Knee Replacement

18 - 44 2 9

45 - 64 25 11

65 – 74 43 27

75 – 84 27 14

85 - older 3 2

1) What is the probability that an orthopedic surgical case selected at random involves

knee surgery?

It's hard to believe you are serious. You were told "About 26% of orthopedic surgeries involves knee problems." Do you not know what that means?

2) What is the probability that a person from ages 18 – 44 who has knee surgery has a

full knee replacement?

How many people are listed in the 18-44 category? How many of those had full knee replacement? What percentage was that? Do you know how a "percentage" is related to a "probability"?

3) What is the probability that a person from 45 – 64 who has knee surgery has a full

knee replacement?

Same as (2)!

4) What is the probability that a person who has knee surgery has a full knee

replacement?

How many total people had knee surgery? How many had full knee surgery? What percentage is that?