Finding the Fourth Proportional to 978.88, 1,468.42 and 285.55

Step by Step Solution

1. Step 1: Write the proportion equation
   978.88 : 1,468.42 = 285.55 : x
2. Step 2: Convert to fraction form
   978.88/1,468.42 = 285.55/x
3. Step 3: Cross multiply
   978.88x = 1,468.42 × 285.55
4. Step 4: Simplify right side
   978.88x = 419,307.33
5. Step 5: Solve for x
   x = 419,307.33/978.88
6. Step 6: Final answer
   x = 428.35