A seller uses faulty weight in place of a 2 kg weight and earns a 25% profit. He claims that he is selling on the cost price in front of the customers but uses a faulty weight. How much error is there in the 2 kg weight to gain 25%?

400 g

25% profit = \(\frac{1}{4}\) ⇒  \(\frac{5}{4}\)

              5 = 2 kg

Now ⇒ \(\frac{2 kg}{5}\) × 4

       = 1.6 kg

differet weight = (2 - 1.6) kg

                     = 400 g