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# A group of 400 people has the following blood type distribution: 140 have blood type O, 90 have blood type A, 120 have blood type B, and 50

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A group of 400 people has the following blood type distribution: 140 have blood type O, 90 have blood type A, 120 have blood type B, and 50 have blood type AB. If a person is selected at random from the group, what is the probability that this person has blood type B?

Guest Jun 5, 2018
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Probability: the amount you want/total.

Since there are a total of 400 people, and you want the probability that the person has blood type B, we need to find the total number of people who have blood type B. In the problem it says 120 people have blood type B, so plugging the values into our formula, we have: $$\frac{120}{400}=\frac{12}{40}=\boxed{{\frac{3}{10}}}$$

tertre  Jun 5, 2018