Finding the Third Proportional to 128.25 and 279.38

Step by Step Solution

1. Step 1: Write the proportion equation
   128.25 : 279.38 = 279.38 : x
2. Step 2: Convert to fraction form
   128.25/279.38 = 279.38/x
3. Step 3: Cross multiply
   128.25x = 279.38 × 279.38
4. Step 4: Simplify right side
   128.25x = 78,050.39
5. Step 5: Solve for x
   x = 78,050.39/128.25
6. Step 6: Final answer
   x = 608.58