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To Verbal Expert.....CR Assumption

by Mo2men » Thu Jul 14, 2016 11:11 am
Two genes BRCA1 and BRCA2 are linked to hereditary breast cancer. Therefore in order to decrease the annual number of mammogram tests administered across a population and to more accurately assess a woman's individual risk of breast cancer, all women should be tested for these genes.

Which of the following is the assumption?

A. Some women who are tested for the two genes will subsequently undergo mammograms on a less frequent basis than they used to.
B. The majority of breast cancer patients have no family history of the disease.
C. Researchers may have identified a third breast cancer gene that is linked with hereditary breast cancer.
D. Women who have these genes have an 90% chance of getting breast cancer while women who don't have these genes have only a 20% chance of getting breast cancer.
E. The presence of BRCA1 and BRCA 2 can explain upto to 50% of hereditary cases
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by OptimusPrep » Thu Jul 14, 2016 8:05 pm
Mo2men wrote:Two genes BRCA1 and BRCA2 are linked to hereditary breast cancer. Therefore in order to decrease the annual number of mammogram tests administered across a population and to more accurately assess a woman's individual risk of breast cancer, all women should be tested for these genes.

Which of the following is the assumption?

A. Some women who are tested for the two genes will subsequently undergo mammograms on a less frequent basis than they used to.
B. The majority of breast cancer patients have no family history of the disease.
C. Researchers may have identified a third breast cancer gene that is linked with hereditary breast cancer.
D. Women who have these genes have an 90% chance of getting breast cancer while women who don't have these genes have only a 20% chance of getting breast cancer.
E. The presence of BRCA1 and BRCA 2 can explain upto to 50% of hereditary cases
Premise: BRCA1 and BRCA2 are linked to hereditary breast cancer.
Conclusion: To reduce mammogram tests and accurately identify risk, women should be tested for these genes.

On looking at the options, only A and D remain.
Option A gives us a reason to assume that if the women are tested for these genes, they will go for the mammogram test on a less frequent basis and thus support our conclusion. Hence the correct option.

Option D on the other hand is a trap option and does not tell us anything about our conclusion of reduction of tests.
Moreover any options with such precise percentages or numbers should be dealt with carefully in an assumption question as they are often not the correct option.

Correct Answer: A
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by GMATGuruNY » Sat Jul 16, 2016 2:16 am
Mo2men wrote:Two genes BRCA1 and BRCA2 are linked to hereditary breast cancer. Therefore in order to decrease the annual number of mammogram tests administered across a population and to more accurately assess a woman's individual risk of breast cancer, all women should be tested for these genes.

Which of the following is the assumption?

A. Some women who are tested for the two genes will subsequently undergo mammograms on a less frequent basis than they used to.
B. The majority of breast cancer patients have no family history of the disease.
C. Researchers may have identified a third breast cancer gene that is linked with hereditary breast cancer.
D. Women who have these genes have an 90% chance of getting breast cancer while women who don't have these genes have only a 20% chance of getting breast cancer.
E. The presence of BRCA1 and BRCA 2 can explain upto to 50% of hereditary cases
Plan: Test all women for the two genes.
Conclusion: There will be a decrease in the annual number of mammograms, allowing doctors to more accurately assess a woman's individual risk of breast cancer.

Apply the NEGATION TEST.
When the correct answer choice is negated, the conclusion will be invalidated.
The opposite of some is NONE.

Answer choice A, negated:
NO women tested for the two genes will undergo mammograms on a less frequent basis than they used to.
In other words:
ALL women tested for the two genes will undergo mammograms as frequently as -- or more frequently than -- they used to.
The negation of A invalidates the conclusion that there will be a decrease in the number of mammograms.
Thus, A is the assumption: WHAT MUST BE TRUE for the conclusion to be valid.

The correct answer is A.
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by Phoenix7 » Mon Jul 18, 2016 7:42 am
IMHO, the difference between the 2 most likely correct options (A and D) is subtle. D gives the probabilities of getting cancer for the tested people - those who tested +ve (for the genes), those who tested -ve. Most likely, the -ve ones will reduce their frequency of tests whereas the +ve will increase it. Because the respective % of people is not given, we can't say if the net will be a decrease or an increase. Option A on the other hand implies that the net will be a decrease although its wording, "Some women who are tested for the two genes...less frequent basis than they used to" doesn't tell us about the women who would take their tests more frequently as a result of the test being +ve. So A is a better option than D, however, only by a small margin.
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by GMATGuruNY » Wed Jul 20, 2016 3:02 am
Phoenix7 wrote:IMHO, the difference between the 2 most likely correct options (A and D) is subtle. D gives the probabilities of getting cancer for the tested people - those who tested +ve (for the genes), those who tested -ve. Most likely, the -ve ones will reduce their frequency of tests whereas the +ve will increase it. Because the respective % of people is not given, we can't say if the net will be a decrease or an increase. Option A on the other hand implies that the net will be a decrease although its wording, "Some women who are tested for the two genes...less frequent basis than they used to" doesn't tell us about the women who would take their tests more frequently as a result of the test being +ve. So A is a better option than D, however, only by a small margin.
An assumption is a statement that MUST BE TRUE for the conclusion to valid.

Conclusion: All women should be tested for the BRCA1 and BRCA2 genes.
D: Women who have these genes have a 90% chance of getting breast cancer.
The percentage in D does not have to be true.
If the BRCA1 and BRCA2 genes indicate a 91% chance or a 92% chance of getting breast cancer, the conclusion that women should be tested for these genes remains valid.
Since D is not a statement that MUST be true, eliminate D.
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