Finding the Fourth Proportional to 12,478.38, 18,720 and 3,712.56

Step by Step Solution

1. Step 1: Write the proportion equation
   12,478.38 : 18,720 = 3,712.56 : x
2. Step 2: Convert to fraction form
   12,478.38/18,720 = 3,712.56/x
3. Step 3: Cross multiply
   12,478.38x = 18,720 × 3,712.56
4. Step 4: Simplify right side
   12,478.38x = 69,499,123.20
5. Step 5: Solve for x
   x = 69,499,123.20/12,478.38
6. Step 6: Final answer
   x = 5,569.56