Finding the Fourth Proportional to 12,919.40, 19,385.50 and 5,128.04

Step by Step Solution

1. Step 1: Write the proportion equation
   12,919.40 : 19,385.50 = 5,128.04 : x
2. Step 2: Convert to fraction form
   12,919.40/19,385.50 = 5,128.04/x
3. Step 3: Cross multiply
   12,919.40x = 19,385.50 × 5,128.04
4. Step 4: Simplify right side
   12,919.40x = 99,409,619.42
5. Step 5: Solve for x
   x = 99,409,619.42/12,919.40
6. Step 6: Final answer
   x = 7,694.60