Finding the Fourth Proportional to 100,665.82, 138,920.43 and 55,345.78

Step by Step Solution

1. Step 1: Write the proportion equation
   100,665.82 : 138,920.43 = 55,345.78 : x
2. Step 2: Convert to fraction form
   100,665.82/138,920.43 = 55,345.78/x
3. Step 3: Cross multiply
   100,665.82x = 138,920.43 × 55,345.78
4. Step 4: Simplify right side
   100,665.82x = 7,688,659,556.29
5. Step 5: Solve for x
   x = 7,688,659,556.29/100,665.82
6. Step 6: Final answer
   x = 76,378.06