Finding the Third Proportional to 85,603.50 and 128,665.50

Step by Step Solution

1. Step 1: Write the proportion equation
   85,603.50 : 128,665.50 = 128,665.50 : x
2. Step 2: Convert to fraction form
   85,603.50/128,665.50 = 128,665.50/x
3. Step 3: Cross multiply
   85,603.50x = 128,665.50 × 128,665.50
4. Step 4: Simplify right side
   85,603.50x = 16,554,810,890.25
5. Step 5: Solve for x
   x = 16,554,810,890.25/85,603.50
6. Step 6: Final answer
   x = 193,389.42