Finding the Third Proportional to 128.56 and 279.06

Step by Step Solution

1. Step 1: Write the proportion equation
   128.56 : 279.06 = 279.06 : x
2. Step 2: Convert to fraction form
   128.56/279.06 = 279.06/x
3. Step 3: Cross multiply
   128.56x = 279.06 × 279.06
4. Step 4: Simplify right side
   128.56x = 77,875.88
5. Step 5: Solve for x
   x = 77,875.88/128.56
6. Step 6: Final answer
   x = 605.74