Finding the Third Proportional to 85.50 and 128.63

Step by Step Solution

1. Step 1: Write the proportion equation
   85.50 : 128.63 = 128.63 : x
2. Step 2: Convert to fraction form
   85.50/128.63 = 128.63/x
3. Step 3: Cross multiply
   85.50x = 128.63 × 128.63
4. Step 4: Simplify right side
   85.50x = 16,544.39
5. Step 5: Solve for x
   x = 16,544.39/85.50
6. Step 6: Final answer
   x = 193.50