Finding the Fourth Proportional to 1,005.71, 1,387.89 and 563.60

Step by Step Solution

1. Step 1: Write the proportion equation
   1,005.71 : 1,387.89 = 563.60 : x
2. Step 2: Convert to fraction form
   1,005.71/1,387.89 = 563.60/x
3. Step 3: Cross multiply
   1,005.71x = 1,387.89 × 563.60
4. Step 4: Simplify right side
   1,005.71x = 782,207.86
5. Step 5: Solve for x
   x = 782,207.86/1,005.71
6. Step 6: Final answer
   x = 777.77