Finding the Fourth Proportional to 64,608.78, 89,155.73 and 39,129.30

Step by Step Solution

1. Step 1: Write the proportion equation
   64,608.78 : 89,155.73 = 39,129.30 : x
2. Step 2: Convert to fraction form
   64,608.78/89,155.73 = 39,129.30/x
3. Step 3: Cross multiply
   64,608.78x = 89,155.73 × 39,129.30
4. Step 4: Simplify right side
   64,608.78x = 3,488,601,403.71
5. Step 5: Solve for x
   x = 3,488,601,403.71/64,608.78
6. Step 6: Final answer
   x = 53,995.78