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Julia is studying potential relationships between one having a pick-up truck and attached ear lobes. Assume a survey of 201 randomly selected persons revealed the following data:

 

The probability of selecting a person with no pick-up truck is 0.784.

The probability of selecting a person with detached ear lobes is 0.684.

The probability of selecting a person with no pick-up truck and detached ear lobes is 0.536.

 

If you were to choose a person at random from the sample, determine the probability they have a pick-up truck given that they have attached ear lobes.

 

(After doing another attempt on my own I ended with the answer of 0.069. Can someone check if this is correct?)

 Dec 21, 2020
 #1
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We would have the best luck of using our information of the total number of people and getting a venn diagram. So let's do that.

 

Favorable/possible = 0.784, so f/201 = 0.784. Thus, there are 201-157.584 = 43.416 people who have pickup trucks.

 

Favorable / possible = 0.684, so f/201 = 0.684. Thus, there are 201-137.484=63.516 people who have attached earlobes (ik right?)

 

favorable / possible = f/#of attached earlobes = f/63.516, and 43.416 + 63.516 = 106.932, so there are 0 people that have both attached earlobes and a pick up truck? I'm probably wrong, just this question is an incorrect question because it doesn't have integer number of people for each case.

 Dec 21, 2020
 #2
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See the Venn below:

 

Total people with attached ealobes = 68 + 248 = 316

      68 of these have a p/u      68 / 316 = 21.5%

 

 

 Dec 21, 2020
 #3
avatar+428 
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That is surely incorrect, as you have stated that the number of people surveyed with attached earlobes is greater than the number of people actually surveyed, which is not possible.

Pangolin14  Dec 21, 2020
 #4
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This Probability is based on percentages

    example   people with no pu truck is given as .784    

       the diagram shows

                 (248+536) / (148 + 68 + 248 + 536) = .784

        you just have to scale the numbers    

            if it makes you feel better, you can just divide all of the numbers in the Venn diagram by 1000

                 .148       .068      .248      .536  

Guest Dec 21, 2020
 #5
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Then it would be   .068 / (.068 + .248) =  21.5%

 

 

If you want actual numbers of the 201 people randomly surveyed people then:

 

 

.68 (201)  / (.068(201) + .248(201) ) = 21.5  %      Do you see now?

Guest Dec 21, 2020
 #6
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.068 (201)  / (.068(201) + .248(201) ) = 21.5  %           sorry....dropped the leading zero there,,,,,   D'Oh!

Guest Dec 22, 2020
 #7
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0

The question does not make sense to me.

The probabilities are based on the sample of 201 people. 

0.784*201 = 157.584

How can you have 0.584 of a person?

 Dec 22, 2020

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