Finding the Fourth Proportional to 1,003.98, 1,385.55 and 561.90

Step by Step Solution

1. Step 1: Write the proportion equation
   1,003.98 : 1,385.55 = 561.90 : x
2. Step 2: Convert to fraction form
   1,003.98/1,385.55 = 561.90/x
3. Step 3: Cross multiply
   1,003.98x = 1,385.55 × 561.90
4. Step 4: Simplify right side
   1,003.98x = 778,540.55
5. Step 5: Solve for x
   x = 778,540.55/1,003.98
6. Step 6: Final answer
   x = 775.45