Finding the Third Proportional to 128.75 and 264.25

Step by Step Solution

1. Step 1: Write the proportion equation
   128.75 : 264.25 = 264.25 : x
2. Step 2: Convert to fraction form
   128.75/264.25 = 264.25/x
3. Step 3: Cross multiply
   128.75x = 264.25 × 264.25
4. Step 4: Simplify right side
   128.75x = 69,828.06
5. Step 5: Solve for x
   x = 69,828.06/128.75
6. Step 6: Final answer
   x = 542.35