The income ratio of Amala, Bina, and Gouri is 3:4:5, and the corresponding interest ratio is 6:5:4. Consequently, the ratio of their interest incomes becomes 18:20:20.
Let the interest incomes of Amala, Bina, and Gouri be 18x, 20x, and 20x, respectively.
Given that Bina's interest income exceeds Amala's by Rs 250,
we can express this as 20x - 18x = 2x = 250.
Solving for x, we find x = 125.
Therefore, the total interest incomes of Amala, Bina, and Gouri amount to 58x, which is equal to 58 × 125 = 7250.