Finding the Fourth Proportional to 1,020.50, 1,408.32 and 554.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,020.50 : 1,408.32 = 554.78 : x
2. Step 2: Convert to fraction form
   1,020.50/1,408.32 = 554.78/x
3. Step 3: Cross multiply
   1,020.50x = 1,408.32 × 554.78
4. Step 4: Simplify right side
   1,020.50x = 781,307.77
5. Step 5: Solve for x
   x = 781,307.77/1,020.50
6. Step 6: Final answer
   x = 765.61