A wrist watch is sold for ₹1,200 at a profit per cent equal to its cost price. Find the cost price of the wrist watch.

₹400 ₹250 ₹350 ₹300

₹300

Let the cost price = x Profit = x% ATQ, Cost price + profit = Selling price x + \(\frac{x × x}{100}\) = 1200 x2 + 100x - 120000 = 0 x2 + 400x - 300x - 120000 = 0 (x + 400) (x - 300) = 0 x = 300