Finding the Third Proportional to 128.25 and 281.25

Step by Step Solution

1. Step 1: Write the proportion equation
   128.25 : 281.25 = 281.25 : x
2. Step 2: Convert to fraction form
   128.25/281.25 = 281.25/x
3. Step 3: Cross multiply
   128.25x = 281.25 × 281.25
4. Step 4: Simplify right side
   128.25x = 79,101.56
5. Step 5: Solve for x
   x = 79,101.56/128.25
6. Step 6: Final answer
   x = 616.78