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UPSC Prelims 2026 CSAT, question 48

Topic: Logical reasoning

Q48

Consider the following statements :

Every red is blue. Every blue is green. Every green is yellow.

Which of the following statements denoted by P, Q and R are correct?

P. Every blue is yellow.

Q. Every red is green.

R. Every red is yellow.

Select the answer using the code given below.

  1. (a) P and Q only
  2. (b) Q and R only
  3. (c) P and R only
  4. (d) P, Q and RCorrect answer

Solution.

Answer: (d) P, Q and R

  1. The premises give the subset chain Red⊆Blue⊆Green⊆Yellow\text{Red} \subseteq \text{Blue} \subseteq \text{Green} \subseteq \text{Yellow}.
  2. By transitivity of inclusion: Blue⊆Yellow\text{Blue} \subseteq \text{Yellow} (so P is correct), Red⊆Green\text{Red} \subseteq \text{Green} (so Q is correct), and Red⊆Yellow\text{Red} \subseteq \text{Yellow} (so R is correct).