Finding the Fourth Proportional to 1,007.98, 1,390.86 and 565.90

Step by Step Solution

1. Step 1: Write the proportion equation
   1,007.98 : 1,390.86 = 565.90 : x
2. Step 2: Convert to fraction form
   1,007.98/1,390.86 = 565.90/x
3. Step 3: Cross multiply
   1,007.98x = 1,390.86 × 565.90
4. Step 4: Simplify right side
   1,007.98x = 787,087.67
5. Step 5: Solve for x
   x = 787,087.67/1,007.98
6. Step 6: Final answer
   x = 780.86