Finding the Third Proportional to 128.06 and 279.89

Step by Step Solution

1. Step 1: Write the proportion equation
   128.06 : 279.89 = 279.89 : x
2. Step 2: Convert to fraction form
   128.06/279.89 = 279.89/x
3. Step 3: Cross multiply
   128.06x = 279.89 × 279.89
4. Step 4: Simplify right side
   128.06x = 78,338.76
5. Step 5: Solve for x
   x = 78,338.76/128.06
6. Step 6: Final answer
   x = 611.72