Finding the Fourth Proportional to 1,389.81, 1,918.11 and 800.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.81 : 1,918.11 = 800.34 : x
2. Step 2: Convert to fraction form
   1,389.81/1,918.11 = 800.34/x
3. Step 3: Cross multiply
   1,389.81x = 1,918.11 × 800.34
4. Step 4: Simplify right side
   1,389.81x = 1,535,126.57
5. Step 5: Solve for x
   x = 1,535,126.57/1,389.81
6. Step 6: Final answer
   x = 1,104.56