Finding the Fourth Proportional to 100,821.72, 139,132.62 and 56,109.72

Step by Step Solution

1. Step 1: Write the proportion equation
   100,821.72 : 139,132.62 = 56,109.72 : x
2. Step 2: Convert to fraction form
   100,821.72/139,132.62 = 56,109.72/x
3. Step 3: Cross multiply
   100,821.72x = 139,132.62 × 56,109.72
4. Step 4: Simplify right side
   100,821.72x = 7,806,692,351.07
5. Step 5: Solve for x
   x = 7,806,692,351.07/100,821.72
6. Step 6: Final answer
   x = 77,430.66