Finding the Fourth Proportional to 1,381.85, 1,906.10 and 821.93

Step by Step Solution

1. Step 1: Write the proportion equation
   1,381.85 : 1,906.10 = 821.93 : x
2. Step 2: Convert to fraction form
   1,381.85/1,906.10 = 821.93/x
3. Step 3: Cross multiply
   1,381.85x = 1,906.10 × 821.93
4. Step 4: Simplify right side
   1,381.85x = 1,566,667.13
5. Step 5: Solve for x
   x = 1,566,667.13/1,381.85
6. Step 6: Final answer
   x = 1,133.75