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Suppose that 3% of all adults suffer from diabetes and that 28% of all adults are obese. Suppose also that 2% of all adults both are obese and suffer from diabetes.

(a) Find the probability that a randomly chosen adult who is obese also suffers from diabetes. Round your answer to decimal places.
(b) Find the probability that a randomly chosen adult is obese, given that he or she suffers from diabetes. Round your answer to decimal places.

1 Answer

3 votes

Answer:

a) There is a 7.14% p(a) probability that a randomly chosen adult who is obese also suffers from diabetes.

b) There is a 66.64% probability of the adult being obese, given that he suffers from diabetes.

Step-by-step explanation:

The problem states that:

28% of all adults are obese. This means that there is a 28% probability of a randomly chosen adult being obese.

3% of all adults suffer from diabetes. This means that there is a 3% probability of a randomly chosen adult suffering from diabetes.

2% of all adults both are obese and suffer from diabetes. This means that there is a 2% probability of a randomly chosen adult both being obese and suffering from diabeters.

(a) Find the probability that a randomly chosen adult who is obese also suffers from diabetes. Round your answer to decimal places:

28% of all adults are obese and 2% of all adults are both obese and suffer from diabetes.

So the probability of a randomly chosen adult who is obese suffering from diabetes is:


P = (2)/(28) = 0.0714

There is a 7.14% probability that a randomly chosen adult who is obese also suffers from diabetes.

(b) Find the probability that a randomly chosen adult is obese, given that he or she suffers from diabetes.

What is the probability of B happening, knowing that A has happened.

It can be calculated by the following formula


P = (P(B).P(A/B))/(P(A))

Where P(B) is the probability of B happening, P(A/B) is the probability of A happening knowing that B happened and P(A) is the probability of A happening.

So:

What is the probability of the adult being obese, given that he suffers from diabetes.

P(B) is the probability of the adult being obese. So
P(B) = 0.28

P(A/B) is the probability of the adult suffering from diabetes, given that he is obese. We found in a) that 7.14% of the adults who are obese also suffer from diabetes. So:


P(A/B) = 0.0714

P(A) is the probability of the adult suffering from diabetes. So:


P(A) = 0.03

Finally


P = (P(B).P(A/B))/(P(A)) = (0.28*0.0714)/(0.03) = 0.6664

There is a 66.64% probability of the adult being obese, given that he suffers from diabetes.

User Mark Ingram
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