Finding the Fourth Proportional to 1,379.61, 1,904.27 and 820.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,379.61 : 1,904.27 = 820.31 : x
2. Step 2: Convert to fraction form
   1,379.61/1,904.27 = 820.31/x
3. Step 3: Cross multiply
   1,379.61x = 1,904.27 × 820.31
4. Step 4: Simplify right side
   1,379.61x = 1,562,078.10
5. Step 5: Solve for x
   x = 1,562,078.10/1,379.61
6. Step 6: Final answer
   x = 1,132.26