A bag has Rs 20 in the form of 1­rupee, 50­paise and 10­paise coins in the ratio of 2:3:5. Find the number of 50­paise coins.

Let the number of 1-rupee, 50-paise and 10-paise coins be $$2x$$ , $$3x$$ and $$5x$$ respectively.

Total amount in the bag = Rs. 20

=> $$(1 \times 2x) + (\frac{50}{100} \times 3x) + (\frac{10}{100} \times 5x) = 20$$

=> $$2x + \frac{3x}{2} + \frac{x}{2} = 20$$

=> $$\frac{4x + 3x + x}{2} = 20$$

=> $$8x = 20 \times 2 = 40$$

=> $$x = \frac{40}{8} = 5$$

$$\therefore$$ Number of 50 paise coins = $$3x = 3 \times 5 = 15$$

=> Ans - (C)