Finding the Fourth Proportional to 1,018.88, 1,406.20 and 810.70

Step by Step Solution

1. Step 1: Write the proportion equation
   1,018.88 : 1,406.20 = 810.70 : x
2. Step 2: Convert to fraction form
   1,018.88/1,406.20 = 810.70/x
3. Step 3: Cross multiply
   1,018.88x = 1,406.20 × 810.70
4. Step 4: Simplify right side
   1,018.88x = 1,140,006.34
5. Step 5: Solve for x
   x = 1,140,006.34/1,018.88
6. Step 6: Final answer
   x = 1,118.88