Finding the Fourth Proportional to 101,290.50, 139,780.89 and 56,578.50

Step by Step Solution

1. Step 1: Write the proportion equation
   101,290.50 : 139,780.89 = 56,578.50 : x
2. Step 2: Convert to fraction form
   101,290.50/139,780.89 = 56,578.50/x
3. Step 3: Cross multiply
   101,290.50x = 139,780.89 × 56,578.50
4. Step 4: Simplify right side
   101,290.50x = 7,908,593,084.87
5. Step 5: Solve for x
   x = 7,908,593,084.87/101,290.50
6. Step 6: Final answer
   x = 78,078.33