Correct Answer - Option 3 : 300
Given:
Denominations of coins = 50 paisa, 25 paisa and 10 paisa
Ratio = 5 ∶ 7 ∶ 9
Total amount = Rs. 309
Calculation:
Let the number of 50 paisa, 25 paisa and 10 paisa coins be 5x, 7x and 9x respectively.
According to question
(5x/2) + (7x/4) + (9x/10) = 309
⇒ (50x + 35x + 18x)/20 = 309
⇒ 103x = 309 × 20
⇒ x = (309 × 20)/103
⇒ x = 3 × 20
⇒ x = 60
Number of 50 paisa coins = 5x
⇒ 5 × 60
⇒ 300
∴ The number of 50 paisa coins are 300.