In a survey, it was found that 10% of the students who are susceptibl
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19 Jun 2024, 13:49
Not a difficult problem but a little bit tricky
Considering that the numbers are in percentages and weird, especially the 9%. Difficult to pik a number to have a net number. However, the answer choices are far apart so we can also work by estimation
TS= total students
These can be divided into two categories : T with tubercolosis and those without NO tubercolosis
Those with T can be divided further into those \(\geq 20\) and those < 20 years
Now, in those kind of question usually is best to look at the phrase we do have in the end, to have the overall total of people involved. In this case
If 9% of the total students are more than or equal to 20 years of age and are susceptible to tuberculosis
So we do have T and \(\geq 20\) are 9%
This means that the other three categories involved T and <20, NT and \(\geq 20\), NT and <20 are 91%
Then we have that the category T and <20 is 10%
Therefore the two categories NT and \(\geq 20\) , NT and <20 are 81%
Of this last categories NT and \(\geq 20\) is 40% = 38.4 and NT and <20 is 48.6
The question is
what percentage of the students, that are 20 years old or more, are not susceptible to tuberculosis?
means \(\frac{38.4}{48.6}=66.6\)
The other answer choices are inferior to this value. So the answer must be E