Finding the Third Proportional to 385,138.50 and 511,155

Step by Step Solution

1. Step 1: Write the proportion equation
   385,138.50 : 511,155 = 511,155 : x
2. Step 2: Convert to fraction form
   385,138.50/511,155 = 511,155/x
3. Step 3: Cross multiply
   385,138.50x = 511,155 × 511,155
4. Step 4: Simplify right side
   385,138.50x = 261,279,434,025
5. Step 5: Solve for x
   x = 261,279,434,025/385,138.50
6. Step 6: Final answer
   x = 678,403.83