Finding the Fourth Proportional to 1,381.65, 1,906.05 and 821.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,381.65 : 1,906.05 = 821.81 : x
2. Step 2: Convert to fraction form
   1,381.65/1,906.05 = 821.81/x
3. Step 3: Cross multiply
   1,381.65x = 1,906.05 × 821.81
4. Step 4: Simplify right side
   1,381.65x = 1,566,401.42
5. Step 5: Solve for x
   x = 1,566,401.42/1,381.65
6. Step 6: Final answer
   x = 1,133.72