HardMath· Problem-Solving and Data Analysis· Probability and conditional probability· SPR
Blood type
Rhesus factor
A
B
AB
O
33
9
3
37
7
2
1
x
Human blood can be classified into four common blood types—A, B, AB, and O. It is also characterized by the presence or absence of the rhesus factor. The table above shows the distribution of blood type and rhesus factor for a group of people. If one of these people who is rhesus negative is chosen at random, the probability that the person has blood type B is . What is the value of x ?
Correct answer: 8
(parsed from the explanation — this source omits an answer key
for this item)
Explanation
The correct answer is 8. In this group, of the people who are rhesus negative have blood type B. The total number of people who are rhesus negative in the group is , and there are 2 people who are rhesus negative with blood type B. Therefore, . Combining like terms on the left-hand side of the equation yields . Multiplying both sides of this equation by 9 yields , and multiplying both sides of this equation by yields . Subtracting 10 from both sides of this equation yields .
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id cb_question_bank:1eb20a8c-7806-4bd7-8d92-aa013d25e954 · question d4413871 · IBN 019746-DC
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