Finding the Fourth Proportional to 1,389.84, 1,918.46 and 800.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.84 : 1,918.46 = 800.61 : x
2. Step 2: Convert to fraction form
   1,389.84/1,918.46 = 800.61/x
3. Step 3: Cross multiply
   1,389.84x = 1,918.46 × 800.61
4. Step 4: Simplify right side
   1,389.84x = 1,535,924.67
5. Step 5: Solve for x
   x = 1,535,924.67/1,389.84
6. Step 6: Final answer
   x = 1,105.11