Finding the Fourth Proportional to 100,443.98, 138,610.75 and 55,121.78

Step by Step Solution

1. Step 1: Write the proportion equation
   100,443.98 : 138,610.75 = 55,121.78 : x
2. Step 2: Convert to fraction form
   100,443.98/138,610.75 = 55,121.78/x
3. Step 3: Cross multiply
   100,443.98x = 138,610.75 × 55,121.78
4. Step 4: Simplify right side
   100,443.98x = 7,640,471,267.14
5. Step 5: Solve for x
   x = 7,640,471,267.14/100,443.98
6. Step 6: Final answer
   x = 76,066.99