Finding the Third Proportional to 128,808 and 261,109.50

Step by Step Solution

1. Step 1: Write the proportion equation
   128,808 : 261,109.50 = 261,109.50 : x
2. Step 2: Convert to fraction form
   128,808/261,109.50 = 261,109.50/x
3. Step 3: Cross multiply
   128,808x = 261,109.50 × 261,109.50
4. Step 4: Simplify right side
   128,808x = 68,178,170,990.25
5. Step 5: Solve for x
   x = 68,178,170,990.25/128,808
6. Step 6: Final answer
   x = 529,300.75