Step 1: Analyse Question StemWe can represent the data given in the question in terms of a Venn diagram, since we have an overlapping region (that of people answering YES for both questions).
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In the Venn diagram, the sum of the four regions inside the diagram should be 100 i.e.,
a + b + c + n = 100
We need to find the value of the overlapping region (or the intersection of the two sets) i.e.
the value of c.Step 2: Analyse Statements Independently (And eliminate options) – AD / BCEStatement 1: Of the respondents who answered Yes to the first question, 40% answered Yes to the second question.
The number of respondents who answered Yes to the first question = a + c
Of these, 40% answered YES to the second question also; therefore, c = 40% of (a + c)
or c =\(\frac{ 2}{5}\) (a+c).
We have no information about the other two regions, b and n. Therefore, we cannot find the value of c uniquely since we do not have sufficient number of independent equations.
Statement 1 alone is insufficient. Answer options A and D can be eliminated.
Statement 2: Of the respondents who answered Yes to at least one question, 30% answered Yes to both questions.
The number of respondents who answered Yes to at least one question = a + b + c
Of these, 30% responded Yes to both questions; therefore, c = 30% of (a+b+c)
We have no information about n. Therefore, we cannot find the value of (a + b + c) and hence the value of c.
Statement 2 alone is insufficient. Answer option B can be eliminated.
Step 3: Analyse Statements by combiningFrom statement 1: c = 2/5 (a+c).
From statement 2: c = 30% of (a+b+c)
Combining the information, we can get an equation in terms of a, b and c. However, we have no information about n and hence cannot find out the values of any of the variables uniquely.
The combination of statements is insufficient. Answer option C can be eliminated.
The correct answer option is E.