Finding the Fourth Proportional to 56,620.31, 78,137.54 and 30,780.60

Step by Step Solution

1. Step 1: Write the proportion equation
   56,620.31 : 78,137.54 = 30,780.60 : x
2. Step 2: Convert to fraction form
   56,620.31/78,137.54 = 30,780.60/x
3. Step 3: Cross multiply
   56,620.31x = 78,137.54 × 30,780.60
4. Step 4: Simplify right side
   56,620.31x = 2,405,120,363.72
5. Step 5: Solve for x
   x = 2,405,120,363.72/56,620.31
6. Step 6: Final answer
   x = 42,478.05