Finding the Fourth Proportional to 1,000.67, 1,380.89 and 558.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,000.67 : 1,380.89 = 558.56 : x
2. Step 2: Convert to fraction form
   1,000.67/1,380.89 = 558.56/x
3. Step 3: Cross multiply
   1,000.67x = 1,380.89 × 558.56
4. Step 4: Simplify right side
   1,000.67x = 771,300.22
5. Step 5: Solve for x
   x = 771,300.22/1,000.67
6. Step 6: Final answer
   x = 770.79