Finding the Fourth Proportional to 1,007.90, 1,390.82 and 565.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,007.90 : 1,390.82 = 565.71 : x
2. Step 2: Convert to fraction form
   1,007.90/1,390.82 = 565.71/x
3. Step 3: Cross multiply
   1,007.90x = 1,390.82 × 565.71
4. Step 4: Simplify right side
   1,007.90x = 786,797.95
5. Step 5: Solve for x
   x = 786,797.95/1,007.90
6. Step 6: Final answer
   x = 780.63