Finding the Third Proportional to 128.57 and 209.46

Step by Step Solution

1. Step 1: Write the proportion equation
   128.57 : 209.46 = 209.46 : x
2. Step 2: Convert to fraction form
   128.57/209.46 = 209.46/x
3. Step 3: Cross multiply
   128.57x = 209.46 × 209.46
4. Step 4: Simplify right side
   128.57x = 43,873.88
5. Step 5: Solve for x
   x = 43,873.88/128.57
6. Step 6: Final answer
   x = 341.25