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Question

A recent survey shows that 65% of tobacco users were advised to stop consuming tobacco. The survey also shows that 3 out of 10 tobacco users attempted to stop using tobacco.
Based only on the information in the above passage, which one of the following options can be logically inferred with certainty?

The correct answer is
A majority of tobacco users who were advised to stop consuming tobacco did not attempt to do so.

Survey Statistics for Inference

The question asks for a conclusion that can be logically inferred with certainty, based only on the provided survey data about tobacco use.

Key Survey Statistics

  • Percentage of tobacco users advised to stop: 65%
  • Proportion of tobacco users who attempted to stop: 3 out of 10, which equals 30%

Inference Options Evaluation

Let T be the total number of tobacco users surveyed.

Group A: Tobacco users advised to stop. The size of this group is $0.65T$.

Group B: Tobacco users who attempted to stop. The size of this group is $0.30T$.

We need to evaluate the statement: "A majority of tobacco users who were advised to stop consuming tobacco did not attempt to do so." This statement is true if the number of users who were advised but did NOT attempt to stop (let's call this group $A \setminus B$) is greater than 50% of the size of Group A.

Range Calculation for Non-Attempting Advised Users

The number of users who were both advised and attempted to stop is the intersection of Group A and Group B ($A \cap B$). The size of this intersection, $|A \cap B|$, can vary.

  • The minimum possible overlap is 0 (if none of the 30% who attempted were among the 65% advised).
  • The maximum possible overlap is the size of the smaller group, which is $0.30T$.

The number of advised users who did NOT attempt to stop is calculated as $|A \setminus B| = |A| - |A \cap B|$.

Considering the range of overlap:

  • If the overlap is maximum ($|A \cap B| = 0.30T$): The number who did not attempt is $0.65T - 0.30T = 0.35T$.
  • If the overlap is minimum ($|A \cap B| = 0$): The number who did not attempt is $0.65T - 0 = 0.65T$.

Therefore, the number of advised users who did not attempt to stop falls between $0.35T$ and $0.65T$.

Majority Condition Check

We need to determine if this number ($|A \setminus B|$) represents a majority (more than 50%) of Group A ($|A| = 0.65T$).

50% of Group A is $0.50 \times 0.65T = 0.325T$.

We check if the calculated range for $|A \setminus B|$ is greater than $0.325T$:

  • The minimum value $0.35T$ is greater than $0.325T$.
  • The maximum value $0.65T$ is also greater than $0.325T$.

Since even the minimum possible number of advised users who did not attempt ($0.35T$) constitutes more than 50% of the advised group ($0.325T$), this statement can be inferred with certainty.

Logical Conclusion from Data

Other options are not verifiable: Option 1 is incorrect because 30% (attempted) is not a majority of 65% (advised). Options 3 and 4 are incorrect because the survey provides data on advice given and attempts made, not successful cessation rates.

Therefore, the only statement that can be logically inferred with certainty is that a majority of tobacco users advised to stop did not attempt to do so.

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Important Questions from Logical Inferences

  1. Based on the statements in (1) – (4), which option/s is/are correct? 
    (1) Thor has a female sibling 
    (2) Thor has a sister 
    (3) Thor has visited New Delhi 
    (4) Thor has visited India

  2. In 2022, June Huh was awarded the Fields medal, which is the highest prize in Mathematics. 
    When he was younger, he was also a poet. He did not win any medals in the International Mathematics Olympiads. He dropped out of college. 
    Based only on the above information, which one of the following statements can be logically inferred with certainty?

  3. Elvesland is a country that has peculiar beliefs and practices. They express almost all their emotions by gifting flowers. For instance, if anyone gifts a white flower to someone, then it is always taken to be a declaration of one's love for that person. In a similar manner, the gifting of a yellow flower to someone often means that one is angry with that person. 

    Based only on the information provided above, which one of the following sets of statement(s) can be logically inferred with certainty? 

    (i) In Elvesland, one always declares one's love by gifting a white flower. 

    (ii) In Elvesland, all emotions are declared by gifting flowers. 

    (iii) In Elvesland, sometimes one expresses one's anger by gifting a flower that is not yellow. 

    (iv) In Elvesland, sometimes one expresses one's love by gifting a white flower.

  4. In a recently conducted national entrance test, boys constituted 65% of those who appeared for the test. Girls constituted the remaining candidates and they accounted for 60% of the qualified candidates.
    Which one of the following is the correct logical inference based on the information provided in the above passage?
  5. A duck named Donald Duck says “All ducks always lie." 

    Based only on the information above, which one of the following statements can be logically inferred with certainty?

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