Finding the Fourth Proportional to 12,478.56, 18,720.72 and 3,713.28

Step by Step Solution

1. Step 1: Write the proportion equation
   12,478.56 : 18,720.72 = 3,713.28 : x
2. Step 2: Convert to fraction form
   12,478.56/18,720.72 = 3,713.28/x
3. Step 3: Cross multiply
   12,478.56x = 18,720.72 × 3,713.28
4. Step 4: Simplify right side
   12,478.56x = 69,515,275.16
5. Step 5: Solve for x
   x = 69,515,275.16/12,478.56
6. Step 6: Final answer
   x = 5,570.78