Finding the Fourth Proportional to 978.11, 1,349.82 and 558.50

Step by Step Solution

1. Step 1: Write the proportion equation
   978.11 : 1,349.82 = 558.50 : x
2. Step 2: Convert to fraction form
   978.11/1,349.82 = 558.50/x
3. Step 3: Cross multiply
   978.11x = 1,349.82 × 558.50
4. Step 4: Simplify right side
   978.11x = 753,867.72
5. Step 5: Solve for x
   x = 753,867.72/978.11
6. Step 6: Final answer
   x = 770.74