Skip to main content
Back to Mathematical Reasoning
JEE Main 2022
Mathematical Reasoning
Mathematical Reasoning
Easy

Question

Consider the following statements: P : I have fever Q: I will not take medicine R\mathrm{R} : I will take rest. The statement "If I have fever, then I will take medicine and I will take rest" is equivalent to :

Options

Solution

Key Concepts and Formulas

  • Implication: PQPQP \to Q \equiv \sim P \vee Q
  • Distributive Law: A(BC)(AB)(AC)A \vee (B \wedge C) \equiv (A \vee B) \wedge (A \vee C)

Step-by-Step Solution

Step 1: Translate the given statement into symbolic form. The statement "If I have fever, then I will take medicine and I will take rest" can be written as P(QR)P \to (Q \wedge R). Here, PP is "I have fever", QQ is "I will take medicine", and RR is "I will take rest". Note that in the question, Q is "I will NOT take medicine". Thus we need to change Q to ~Q to match the question. The statement is then P(QR)P \to (\sim Q \wedge R).

Step 2: Apply the implication equivalence. We know that PQPQP \to Q \equiv \sim P \vee Q. Applying this to our statement, we get: P(QR)P(QR)P \to (\sim Q \wedge R) \equiv \sim P \vee (\sim Q \wedge R) This step uses the implication equivalence formula to rewrite the "if-then" statement using "or" and negation.

Step 3: Apply the distributive law. We can distribute the "or" (\vee) over the "and" (\wedge) using the distributive law: A(BC)(AB)(AC)A \vee (B \wedge C) \equiv (A \vee B) \wedge (A \vee C). Applying this to our expression, we get: P(QR)(PQ)(PR)\sim P \vee (\sim Q \wedge R) \equiv (\sim P \vee \sim Q) \wedge (\sim P \vee R) This step transforms the expression into a form that matches one of the answer choices.

Common Mistakes & Tips

  • Remember the correct equivalence for implication: PQPQP \to Q \equiv \sim P \vee Q. A common mistake is to mix up the negation.
  • Carefully note the given definitions of P, Q, and R. Pay attention to negations. The question statement says Q: I will not take medicine.
  • The distributive law is a useful tool for manipulating logical expressions. Make sure to apply it correctly.

Summary

We started with the given statement in symbolic form, P(QR)P \to (\sim Q \wedge R). We then applied the implication equivalence to rewrite it as P(QR)\sim P \vee (\sim Q \wedge R). Finally, we used the distributive law to obtain (PQ)(PR)(\sim P \vee \sim Q) \wedge (\sim P \vee R). This matches option (A).

Final Answer

The final answer is (PQ)(PR)(\sim P \vee \sim Q) \wedge (\sim P \vee R), which corresponds to option (A). The final answer is \boxed{((\sim P) \vee \sim Q) \wedge((\sim P) \vee R)}.

Practice More Mathematical Reasoning Questions

View All Questions