Finding the Fourth Proportional to 1,003.78, 1,385.15 and 561.68

Step by Step Solution

1. Step 1: Write the proportion equation
   1,003.78 : 1,385.15 = 561.68 : x
2. Step 2: Convert to fraction form
   1,003.78/1,385.15 = 561.68/x
3. Step 3: Cross multiply
   1,003.78x = 1,385.15 × 561.68
4. Step 4: Simplify right side
   1,003.78x = 778,011.05
5. Step 5: Solve for x
   x = 778,011.05/1,003.78
6. Step 6: Final answer
   x = 775.08