Finding the Fourth Proportional to 42,471.60, 63,691.20 and 12,879.60

Step by Step Solution

1. Step 1: Write the proportion equation
   42,471.60 : 63,691.20 = 12,879.60 : x
2. Step 2: Convert to fraction form
   42,471.60/63,691.20 = 12,879.60/x
3. Step 3: Cross multiply
   42,471.60x = 63,691.20 × 12,879.60
4. Step 4: Simplify right side
   42,471.60x = 820,317,179.52
5. Step 5: Solve for x
   x = 820,317,179.52/42,471.60
6. Step 6: Final answer
   x = 19,314.49