Finding the Fourth Proportional to 978.18, 1,349.82 and 558.56

Step by Step Solution

1. Step 1: Write the proportion equation
   978.18 : 1,349.82 = 558.56 : x
2. Step 2: Convert to fraction form
   978.18/1,349.82 = 558.56/x
3. Step 3: Cross multiply
   978.18x = 1,349.82 × 558.56
4. Step 4: Simplify right side
   978.18x = 753,948.71
5. Step 5: Solve for x
   x = 753,948.71/978.18
6. Step 6: Final answer
   x = 770.77