Finding the Fourth Proportional to 1,380.81, 1,906.21 and 821.46

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.81 : 1,906.21 = 821.46 : x
2. Step 2: Convert to fraction form
   1,380.81/1,906.21 = 821.46/x
3. Step 3: Cross multiply
   1,380.81x = 1,906.21 × 821.46
4. Step 4: Simplify right side
   1,380.81x = 1,565,875.27
5. Step 5: Solve for x
   x = 1,565,875.27/1,380.81
6. Step 6: Final answer
   x = 1,134.03