A bag has Rs 11 in the form of 1-rupee, 50-paise and 10-paise coins in the ratio of 4:2:5. Find the number of 50-paise coins.

Let the number of 1-rupee, 50-paise and 10-paise coins be $$4x$$ , $$2x$$ and $$5x$$ respectively.

Total amount in the bag = Rs. 11

=> $$(1 \times 4x) + (\frac{50}{100} \times 2x) + (\frac{10}{100} \times 5x) = 11$$

=> $$4x + x + \frac{x}{2} = 11$$

=> $$\frac{8x + 2x + x}{2} = 11$$

=> $$11x = 11 \times 2 = 22$$

=> $$x = \frac{22}{11} = 2$$

$$\therefore$$ Number of 50 paise coins = $$2x = 2 \times 2 = 4$$

=> Ans - (C)