Finding the Fourth Proportional to 1,389.81, 1,918.07 and 830.27

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.81 : 1,918.07 = 830.27 : x
2. Step 2: Convert to fraction form
   1,389.81/1,918.07 = 830.27/x
3. Step 3: Cross multiply
   1,389.81x = 1,918.07 × 830.27
4. Step 4: Simplify right side
   1,389.81x = 1,592,519.74
5. Step 5: Solve for x
   x = 1,592,519.74/1,389.81
6. Step 6: Final answer
   x = 1,145.85