Finding the Fourth Proportional to 12,488.50, 18,732.31 and 3,128.60

Step by Step Solution

1. Step 1: Write the proportion equation
   12,488.50 : 18,732.31 = 3,128.60 : x
2. Step 2: Convert to fraction form
   12,488.50/18,732.31 = 3,128.60/x
3. Step 3: Cross multiply
   12,488.50x = 18,732.31 × 3,128.60
4. Step 4: Simplify right side
   12,488.50x = 58,605,856.30
5. Step 5: Solve for x
   x = 58,605,856.30/12,488.50
6. Step 6: Final answer
   x = 4,692.79