Finding the Fourth Proportional to 100,820.72, 139,131.24 and 56,108.72

Step by Step Solution

1. Step 1: Write the proportion equation
   100,820.72 : 139,131.24 = 56,108.72 : x
2. Step 2: Convert to fraction form
   100,820.72/139,131.24 = 56,108.72/x
3. Step 3: Cross multiply
   100,820.72x = 139,131.24 × 56,108.72
4. Step 4: Simplify right side
   100,820.72x = 7,806,475,788.41
5. Step 5: Solve for x
   x = 7,806,475,788.41/100,820.72
6. Step 6: Final answer
   x = 77,429.28