Finding the Third Proportional to 128,839.50 and 189,405

Step by Step Solution

1. Step 1: Write the proportion equation
   128,839.50 : 189,405 = 189,405 : x
2. Step 2: Convert to fraction form
   128,839.50/189,405 = 189,405/x
3. Step 3: Cross multiply
   128,839.50x = 189,405 × 189,405
4. Step 4: Simplify right side
   128,839.50x = 35,874,254,025
5. Step 5: Solve for x
   x = 35,874,254,025/128,839.50
6. Step 6: Final answer
   x = 278,441.43