Finding the Third Proportional to 138,309 and 213,603.75

Step by Step Solution

1. Step 1: Write the proportion equation
   138,309 : 213,603.75 = 213,603.75 : x
2. Step 2: Convert to fraction form
   138,309/213,603.75 = 213,603.75/x
3. Step 3: Cross multiply
   138,309x = 213,603.75 × 213,603.75
4. Step 4: Simplify right side
   138,309x = 45,626,562,014.06
5. Step 5: Solve for x
   x = 45,626,562,014.06/138,309
6. Step 6: Final answer
   x = 329,888.60