Finding the Third Proportional to 99.75 and 128.75

Step by Step Solution

1. Step 1: Write the proportion equation
   99.75 : 128.75 = 128.75 : x
2. Step 2: Convert to fraction form
   99.75/128.75 = 128.75/x
3. Step 3: Cross multiply
   99.75x = 128.75 × 128.75
4. Step 4: Simplify right side
   99.75x = 16,576.56
5. Step 5: Solve for x
   x = 16,576.56/99.75
6. Step 6: Final answer
   x = 166.18