Twenty-five percent of Reena's yearly income is equal to seventy-five percent of Anubhav's monthly income. If Anubhav's yearly income is ₹ 240000, what is Reena's monthly income?

### Concept & Strategy This problem tests careful reading and unit consistency. The mathematical equations are simple, but the trap lies in the constant switching between "monthly" and "yearly" income terms. Always normalize all variables to the same time frame (either all monthly or all yearly) before equating them. ### Step-by-step Solution **Given:** Anubhav's yearly income = ₹ 2,40,000 First, find Anubhav's monthly income: $$ \text{Anubhav's Monthly} = \frac{240000}{12} = 20000 $$ Set up the equation provided in the first sentence: $$ 25\% \text{ of Reena's Yearly} = 75\% \text{ of Anubhav's Monthly} $$ $$ 0.25 \times \text{Reena's Yearly} = 0.75 \times 20000 $$ Calculate the right side: $$ 75\% \text{ of } 20000 = 15000 $$ Substitute back to find Reena's yearly income: $$ 0.25 \times \text{Reena's Yearly} = 15000 $$ $$ \frac{1}{4} \times \text{Reena's Yearly} = 15000 $$ $$ \text{Reena's Yearly} = 15000 \times 4 = 60000 $$ The question specifically asks for Reena's *monthly* income: $$ \text{Reena's Monthly} = \frac{\text{Reena's Yearly}}{12} $$ $$ \text{Reena's Monthly} = \frac{60000}{12} = 5000 $$ Reena's monthly income is ₹ 5000. Looking at the options (60000, 12000, 5200), ₹ 5000 is not listed. ### Exam Strategy & Shortcut Simplify the percentages immediately. 25% is $ \frac{1}{4} $ and 75% is $ \frac{3}{4} $. $ \frac{1}{4} $ Reena (Yr) = $ \frac{3}{4} $ Anubhav (Mo). Multiply both sides by 4: Reena (Yr) = $3 \times$ Anubhav (Mo). Anubhav's monthly = $ 240000 \div 12 = 20000 $. Reena's yearly = $ 3 \times 20000 = 60000 $. Reena's monthly = $ 60000 \div 12 = 5000 $. This streamlined mental math reduces the chance of getting lost in decimals. ### Common Pitfall The primary pitfall is calculating Reena's yearly income as ₹ 60,000 and immediately selecting Option A, completely missing that the question asks for her *monthly* income. Exam setters specifically place intermediate calculation results in the options to catch rushed students. ### Final Answer **Therefore, the correct answer is None of these.**