In this aptitude (simplification and marginal analysis) question from basic microeconomics, one more cobbler is hired and output rises from 50 pairs per day to 55 pairs per day. The selling price per pair must be reduced from ₹3200 to ₹3000 to sell the additional output. Using this information, compute the marginal revenue product (MRP) of the last cobbler.

Introduction / Context:
This question links arithmetic simplification with a key concept in microeconomics, namely marginal revenue product. Firms often decide whether to hire an extra worker by comparing the additional revenue generated by that worker with the extra cost of hiring. Here we consider a shoe making unit that employs cobblers and adjusts its selling price when output changes.

Given Data / Assumptions:
Initial output is 50 pairs of shoes per day at a price of ₹3200 per pair.
After hiring one more cobbler, output increases to 55 pairs per day and the price falls to ₹3000 per pair.
Marginal revenue product is defined as the change in total revenue due to employing one additional unit of labour, here the last cobbler.

Concept / Approach:
Total revenue equals price multiplied by quantity sold. The marginal revenue product of the last cobbler is the difference between total revenue after hiring the additional cobbler and total revenue before hiring. Even though the price falls, the increased quantity may still raise total revenue. We calculate both revenue levels and then find the change.

Step-by-Step Solution:
Initial situation: quantity = 50 pairs, price = ₹3200 per pair. Initial total revenue = 50 * 3200 = ₹160000. New situation: quantity = 55 pairs, price = ₹3000 per pair. New total revenue = 55 * 3000 = ₹165000. Marginal revenue product (MRP) of the last cobbler = new total revenue - initial total revenue. MRP = ₹165000 - ₹160000 = ₹5000.

Verification / Alternative check:
We can think in terms of incremental units. The additional cobbler is associated with an extra 5 pairs sold per day. At the new price of ₹3000 per pair, these 5 pairs generate 5 * 3000 = ₹15000. However, lowering the price from ₹3200 to ₹3000 on the original 50 pairs reduces revenue by 50 * 200 = ₹10000. The net gain is ₹15000 - ₹10000 = ₹5000, which matches the earlier calculation for marginal revenue product.

Why Other Options Are Wrong:
Option ₹1000 is too small and might come from miscomputing the price drop effect. Option ₹4000 could arise from a partial calculation ignoring some revenue change. Option ₹200 corresponds loosely to the price change per pair, not total revenue. Option ₹0 would imply no change in total revenue, which is clearly not the case once we compute it exactly. Only ₹5000 accurately represents the net increase in revenue due to hiring the additional cobbler.

Common Pitfalls:
A common mistake is to focus only on extra units sold at the new price and ignore the loss in revenue on previous units due to price reduction. Another error is to confuse marginal physical product (extra units produced) with marginal revenue product (extra revenue). To avoid these problems, always compute total revenue before and after the change and then subtract.

Final Answer:
The marginal revenue product of the last cobbler is ₹5000 per day.