Finding the Third Proportional to 558 and 1,315.25

Step by Step Solution

1. Step 1: Write the proportion equation
   558 : 1,315.25 = 1,315.25 : x
2. Step 2: Convert to fraction form
   558/1,315.25 = 1,315.25/x
3. Step 3: Cross multiply
   558x = 1,315.25 × 1,315.25
4. Step 4: Simplify right side
   558x = 1,729,882.56
5. Step 5: Solve for x
   x = 1,729,882.56/558
6. Step 6: Final answer
   x = 3,100.15