Finding the Fourth Proportional to 1,380.25, 1,904.97 and 820.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.25 : 1,904.97 = 820.81 : x
2. Step 2: Convert to fraction form
   1,380.25/1,904.97 = 820.81/x
3. Step 3: Cross multiply
   1,380.25x = 1,904.97 × 820.81
4. Step 4: Simplify right side
   1,380.25x = 1,563,618.43
5. Step 5: Solve for x
   x = 1,563,618.43/1,380.25
6. Step 6: Final answer
   x = 1,132.85