Finding the Fourth Proportional to 1,009.57, 1,392.09 and 636.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,009.57 : 1,392.09 = 636.10 : x
2. Step 2: Convert to fraction form
   1,009.57/1,392.09 = 636.10/x
3. Step 3: Cross multiply
   1,009.57x = 1,392.09 × 636.10
4. Step 4: Simplify right side
   1,009.57x = 885,508.45
5. Step 5: Solve for x
   x = 885,508.45/1,009.57
6. Step 6: Final answer
   x = 877.11