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Bunuel
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Bunuel
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from 1) its only saying half of computers with built in modems do not have infrared ports. how its conveying computers with modem are 50%?

(1) Half of the computers that are equipped with built-in modems do not have infrared ports. Look at the double set matrix below:



As you can see, the value of the yellow box cannot be determined. Not sufficient.

To elaborate further: since half of the computers with built-in modems do not have infra-red ports, the other half of the computers with built-in modems must have infra-red ports. Therefore, the two boxes in the "Modem" column are equal. Given that the number of computers with both modems and infra-red ports is 25, the number of computers with modems but without infra-red ports must also be 25.
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I have edited the question and the solution by adding more details to enhance its clarity. I hope it is now easier to understand.
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gmatophobia

can you suggest where I am doing wrong?
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Hey, the problem with your approach is that while you have assumed that the total number of computers with modem ports is x, you have also assumed that this makes the IR port devices to be 100-x.
That would not be the case.

Because we also need to have a count of devices that are not equipped with either of the ports.
That means Total Modems + Total IR cannot be equal to 100.

Hope this helps.
Can,Will
gmatophobia

can you suggest where I am doing wrong?
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I felt that statement 2 alone is sufficient if we use a venn diagram modem (incl infea red) is 25 and infra red withoiut modem is 35.. so infrared or modem is 25+35= 60 therefore neither is 100-60 =40
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Hello, the problem with your approach is, 100-60 will not give you neither.
100-60 will give you the number of computer that don't have IR. It is a mix of computers that has modems and without modems.

40 = number of computers with modem without IR + number of computers without either
PriyankaGmatIMD
I felt that statement 2 alone is sufficient if we use a venn diagram modem (incl infea red) is 25 and infra red withoiut modem is 35.. so infrared or modem is 25+35= 60 therefore neither is 100-60 =40
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