Finding the Third Proportional to 128.25 and 198.56

Step by Step Solution

1. Step 1: Write the proportion equation
   128.25 : 198.56 = 198.56 : x
2. Step 2: Convert to fraction form
   128.25/198.56 = 198.56/x
3. Step 3: Cross multiply
   128.25x = 198.56 × 198.56
4. Step 4: Simplify right side
   128.25x = 39,427.07
5. Step 5: Solve for x
   x = 39,427.07/128.25
6. Step 6: Final answer
   x = 307.42