Finding the Fourth Proportional to 1,007.64, 1,390.61 and 565.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,007.64 : 1,390.61 = 565.57 : x
2. Step 2: Convert to fraction form
   1,007.64/1,390.61 = 565.57/x
3. Step 3: Cross multiply
   1,007.64x = 1,390.61 × 565.57
4. Step 4: Simplify right side
   1,007.64x = 786,484.47
5. Step 5: Solve for x
   x = 786,484.47/1,007.64
6. Step 6: Final answer
   x = 780.52