Finding the Third Proportional to 258,120 and 378,715.50

Step by Step Solution

1. Step 1: Write the proportion equation
   258,120 : 378,715.50 = 378,715.50 : x
2. Step 2: Convert to fraction form
   258,120/378,715.50 = 378,715.50/x
3. Step 3: Cross multiply
   258,120x = 378,715.50 × 378,715.50
4. Step 4: Simplify right side
   258,120x = 143,425,429,940.25
5. Step 5: Solve for x
   x = 143,425,429,940.25/258,120
6. Step 6: Final answer
   x = 555,654.08