Finding the Fourth Proportional to 1,389.75, 1,917.69 and 830.14

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.75 : 1,917.69 = 830.14 : x
2. Step 2: Convert to fraction form
   1,389.75/1,917.69 = 830.14/x
3. Step 3: Cross multiply
   1,389.75x = 1,917.69 × 830.14
4. Step 4: Simplify right side
   1,389.75x = 1,591,951.18
5. Step 5: Solve for x
   x = 1,591,951.18/1,389.75
6. Step 6: Final answer
   x = 1,145.49