Finding the Fourth Proportional to 1,389.99, 1,918.17 and 800.58

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.99 : 1,918.17 = 800.58 : x
2. Step 2: Convert to fraction form
   1,389.99/1,918.17 = 800.58/x
3. Step 3: Cross multiply
   1,389.99x = 1,918.17 × 800.58
4. Step 4: Simplify right side
   1,389.99x = 1,535,648.54
5. Step 5: Solve for x
   x = 1,535,648.54/1,389.99
6. Step 6: Final answer
   x = 1,104.79