A bag has Rs 30.8 in the form of 1 rupee, 50 paise and 10 paise coins in the ratio of 6:3:2. What is the number of 50 paise coins?

Let the number of 1 rupee, 50 paise and 10 paise coins be $$6x , 3x , 2x$$ respectively

Total amount in the bag = Rs 30.8

=> $$(1 \times 6x) + (\frac{50}{100} \times 3x) + (\frac{10}{100} \times 2x) = 30.8$$

=> $$6x + \frac{3x}{2} + \frac{x}{5} = 30.8$$

=> $$\frac{60x + 15x + 2x}{10} = 30.8$$

=> $$77x = 30.8 \times 10 = 308$$

=> $$x = \frac{308}{77} = 4$$

$$\therefore$$ Number of 50 paise coins = $$3 \times 4 = 12$$