Finding the Fourth Proportional to 1,380.09, 1,904.78 and 820.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.09 : 1,904.78 = 820.89 : x
2. Step 2: Convert to fraction form
   1,380.09/1,904.78 = 820.89/x
3. Step 3: Cross multiply
   1,380.09x = 1,904.78 × 820.89
4. Step 4: Simplify right side
   1,380.09x = 1,563,614.85
5. Step 5: Solve for x
   x = 1,563,614.85/1,380.09
6. Step 6: Final answer
   x = 1,132.98