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The table above represents 100 people grouped by their blood types.

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Bunuel
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The table above represents 100 people grouped by their blood types. [#permalink] New post   16 Aug 2023, 09:00
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The table above represents 100 people grouped by their blood types. The table also shows, for each blood type, the number of people who have a negative Rh factor (Rh-) and the number of people who have a positive Rh factor (Rh+). If 1 person is chosen at random from this group of 100 people, what is the probability that the person chosen has blood type AB or has a negative Rh factor?

A. 0.04
B. 0.19
C. 0.20
D. 0.21
E. 0.99

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kanishkakarpe
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Re: The table above represents 100 people grouped by their blood types. [#permalink] New post   16 Aug 2023, 10:09
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It is important to note that there's an over lap between the sets. We do have one person with group AB & negative Rh factor.

For Probability(AB) or Probability(-Rh) = P(AB) + P(-Rh) - P(AB & -Rh) =\( \frac{17+ 4 -1}{100 }\) = 0.2
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Re: The table above represents 100 people grouped by their blood types. [#permalink] New post   16 Aug 2023, 12:39
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Bunuel wrote:

The table above represents 100 people grouped by their blood types. The table also shows, for each blood type, the number of people who have a negative Rh factor (Rh-) and the number of people who have a positive Rh factor (Rh+). If 1 person is chosen at random from this group of 100 people, what is the probability that the person chosen has blood type AB or has a negative Rh factor?

A. 0.04
B. 0.19
C. 0.20
D. 0.21
E. 0.99

Show Spoiler
Attachment:
2023-07-28_00-07-10.png


  • Number of people having blood group AB = 4
  • Number of people who have a negative Rh factor (Rh-) = 17

Total = 17 + 4 = 21

However, we have calculated people having blood group AB and those who have a negative Rh factor (Rh-) twice. Hence, we have to subtract the number of such individuals once.

21 - 1 = 20

Required Probability = \(\frac{20}{100} = 0.20\)

Option C
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Re: The table above represents 100 people grouped by their blood types. [#permalink] New post   20 Aug 2023, 17:07
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Bunuel wrote:

The table above represents 100 people grouped by their blood types. The table also shows, for each blood type, the number of people who have a negative Rh factor (Rh-) and the number of people who have a positive Rh factor (Rh+). If 1 person is chosen at random from this group of 100 people, what is the probability that the person chosen has blood type AB or has a negative Rh factor?

A. 0.04
B. 0.19
C. 0.20
D. 0.21
E. 0.99


To answer this question, we can use the classical probability formula:

probability = favorable/total

favorable = #(AB or RH-) = #AB + #RH - #(AB and RH-) =
4 + 17 – 1 = 20

total = 100

probability = 20/100 = 1/5 = 0.2

Answer: C
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Re: The table above represents 100 people grouped by their blood types. [#permalink] New post   08 Apr 2024, 12:30
kanishkakarpe wrote:
It is important to note that there's an over lap between the sets. We do have one person with group AB & negative Rh factor.

For Probability(AB) or Probability(-Rh) = P(AB) + P(-Rh) - P(AB & -Rh) =\( \frac{17+ 4 -1}{100 }\) = 0.2

­
Should it not be 0.19? The question asks for a person with group AB OR a negative Rh factor -- So we should exclude P(AB; -Rh) twice, for 0.17+0.4-0.2=0.19

Answer B seems correct (though, of course, Option C is shown as correct)
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Re: The table above represents 100 people grouped by their blood types. [#permalink] New post   09 Apr 2024, 02:21
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mattsu wrote:

The table above represents 100 people grouped by their blood types. The table also shows, for each blood type, the number of people who have a negative Rh factor (Rh-) and the number of people who have a positive Rh factor (Rh+). If 1 person is chosen at random from this group of 100 people, what is the probability that the person chosen has blood type AB or has a negative Rh factor?

A. 0.04
B. 0.19
C. 0.20
D. 0.21
E. 0.99
­
Should it not be 0.19? The question asks for a person with group AB OR a negative Rh factor -- So we should exclude P(AB; -Rh) twice, for 0.17+0.4-0.2=0.19

Answer B seems correct (though, of course, Option C is shown as correct)

­
In mathematics, 'or', unless explicitly specified otherwise, means an inclusive 'or', encompassing both condition 1, condition 2, or both conditions. Thus, when referring to individuals with blood type AB or a negative Rh factor, it includes individuals with blood type AB, individuals with a negative Rh factor, or those who have both characteristics. The total number of people having either one or both conditions is 17 + 3 = 20, resulting in a probability of 20/100.

Hope this helps.­
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Re: The table above represents 100 people grouped by their blood types. [#permalink]
09 Apr 2024, 02:21
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