Finding the Third Proportional to 255.88 and 406.88

Step by Step Solution

1. Step 1: Write the proportion equation
   255.88 : 406.88 = 406.88 : x
2. Step 2: Convert to fraction form
   255.88/406.88 = 406.88/x
3. Step 3: Cross multiply
   255.88x = 406.88 × 406.88
4. Step 4: Simplify right side
   255.88x = 165,547.27
5. Step 5: Solve for x
   x = 165,547.27/255.88
6. Step 6: Final answer
   x = 646.98