Finding the Fourth Proportional to 1,390.33, 1,918.19 and 830.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.33 : 1,918.19 = 830.89 : x
2. Step 2: Convert to fraction form
   1,390.33/1,918.19 = 830.89/x
3. Step 3: Cross multiply
   1,390.33x = 1,918.19 × 830.89
4. Step 4: Simplify right side
   1,390.33x = 1,593,804.89
5. Step 5: Solve for x
   x = 1,593,804.89/1,390.33
6. Step 6: Final answer
   x = 1,146.35