Finding the Fourth Proportional to 1,389.91, 1,917.76 and 830.29

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.91 : 1,917.76 = 830.29 : x
2. Step 2: Convert to fraction form
   1,389.91/1,917.76 = 830.29/x
3. Step 3: Cross multiply
   1,389.91x = 1,917.76 × 830.29
4. Step 4: Simplify right side
   1,389.91x = 1,592,296.95
5. Step 5: Solve for x
   x = 1,592,296.95/1,389.91
6. Step 6: Final answer
   x = 1,145.61