The cost of 7 tables and 12 chairs together is Rs 48,250. Assuming that the cost of each table and each chair remains the same, what will be the total cost of buying 21 tables and 36 chairs?

Introduction / Context:
This arithmetic reasoning question checks understanding of proportionality and linear scaling in cost problems. The combined cost of a certain number of tables and chairs is given, and you are asked to find the cost of a larger set of tables and chairs that has the same ratio between tables and chairs. Because the numbers of tables and chairs both increase by the same factor, the total cost scales by exactly the same factor.

Given Data / Assumptions:

• The cost of 7 tables and 12 chairs together is Rs 48,250.
• The cost per table and the cost per chair remain constant.
• We want the cost of 21 tables and 36 chairs.
• Note that 21 = 3 * 7 and 36 = 3 * 12, so the quantities are scaled by a factor of 3.

Concept / Approach:
If both the number of tables and the number of chairs are multiplied by the same integer factor, and the unit costs stay the same, then the total cost is also multiplied by that same factor. Instead of solving separately for the price of a table and the price of a chair, we can directly scale up the combined cost. This approach saves time and reduces algebraic effort in exam settings.

Step-by-Step Solution:
Step 1: Observe that the original combination is 7 tables and 12 chairs for Rs 48,250. Step 2: The new requirement is 21 tables and 36 chairs. Step 3: Note that 21 is three times 7 and 36 is three times 12. Step 4: Because each item has the same price as before, the cost of 21 tables and 36 chairs will be three times the cost of 7 tables and 12 chairs. Step 5: Multiply the total cost by 3: 48,250 * 3. Step 6: 48,250 * 3 = 144,750. Step 7: Therefore, the cost of 21 tables and 36 chairs is Rs 1,44,750.

Verification / Alternative check:
If desired, one can let the cost of one table be T and one chair be C. Then 7T + 12C = 48,250. For 21 tables and 36 chairs, the total cost is 21T + 36C = 3(7T + 12C) = 3 * 48,250 = 144,750. This algebraic check confirms that simple scaling by 3 is valid and that the final cost is correct.

Why Other Options Are Wrong:
Option B Rs 2,35,745 and option C Rs 89,489 are not simple multiples of the original total and do not correspond to a neat scaling of both quantities by an integer factor. Option D Rs 74,256 is too low and again is not equal to 48,250 multiplied by any small integer. None of these alternatives maintain the proportional relationship between quantities and cost.

Common Pitfalls:
A common mistake is to attempt to compute the cost of a single table and a single chair by solving two equations, even though only one combined equation is effectively given. This leads to unnecessary algebra. Recognizing that both quantities are multiplied by the same factor and hence the total cost also scales by the same factor simplifies such questions considerably.

Final Answer:
The total cost of 21 tables and 36 chairs is Rs 1,44,750.