Finding the Fourth Proportional to 1,007.91, 1,390.89 and 565.86

Step by Step Solution

1. Step 1: Write the proportion equation
   1,007.91 : 1,390.89 = 565.86 : x
2. Step 2: Convert to fraction form
   1,007.91/1,390.89 = 565.86/x
3. Step 3: Cross multiply
   1,007.91x = 1,390.89 × 565.86
4. Step 4: Simplify right side
   1,007.91x = 787,049.02
5. Step 5: Solve for x
   x = 787,049.02/1,007.91
6. Step 6: Final answer
   x = 780.87