Finding the Fourth Proportional to 1,009.86, 1,393.56 and 561.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,009.86 : 1,393.56 = 561.72 : x
2. Step 2: Convert to fraction form
   1,009.86/1,393.56 = 561.72/x
3. Step 3: Cross multiply
   1,009.86x = 1,393.56 × 561.72
4. Step 4: Simplify right side
   1,009.86x = 782,790.52
5. Step 5: Solve for x
   x = 782,790.52/1,009.86
6. Step 6: Final answer
   x = 775.15