Finding the Third Proportional to 128,518.50 and 278,488.50

Step by Step Solution

1. Step 1: Write the proportion equation
   128,518.50 : 278,488.50 = 278,488.50 : x
2. Step 2: Convert to fraction form
   128,518.50/278,488.50 = 278,488.50/x
3. Step 3: Cross multiply
   128,518.50x = 278,488.50 × 278,488.50
4. Step 4: Simplify right side
   128,518.50x = 77,555,844,632.25
5. Step 5: Solve for x
   x = 77,555,844,632.25/128,518.50
6. Step 6: Final answer
   x = 603,460.55