Finding the Fourth Proportional to 137,139.20, 189,432.78 and 105,253.28

Step by Step Solution

1. Step 1: Write the proportion equation
   137,139.20 : 189,432.78 = 105,253.28 : x
2. Step 2: Convert to fraction form
   137,139.20/189,432.78 = 105,253.28/x
3. Step 3: Cross multiply
   137,139.20x = 189,432.78 × 105,253.28
4. Step 4: Simplify right side
   137,139.20x = 19,938,421,434.52
5. Step 5: Solve for x
   x = 19,938,421,434.52/137,139.20
6. Step 6: Final answer
   x = 145,388.20