Finding the Fourth Proportional to 1,380.05, 1,904.28 and 820.41

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.05 : 1,904.28 = 820.41 : x
2. Step 2: Convert to fraction form
   1,380.05/1,904.28 = 820.41/x
3. Step 3: Cross multiply
   1,380.05x = 1,904.28 × 820.41
4. Step 4: Simplify right side
   1,380.05x = 1,562,290.35
5. Step 5: Solve for x
   x = 1,562,290.35/1,380.05
6. Step 6: Final answer
   x = 1,132.05