Finding the Fourth Proportional to 1,007.61, 1,390.52 and 565.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,007.61 : 1,390.52 = 565.55 : x
2. Step 2: Convert to fraction form
   1,007.61/1,390.52 = 565.55/x
3. Step 3: Cross multiply
   1,007.61x = 1,390.52 × 565.55
4. Step 4: Simplify right side
   1,007.61x = 786,405.08
5. Step 5: Solve for x
   x = 786,405.08/1,007.61
6. Step 6: Final answer
   x = 780.47