Finding the Fourth Proportional to 1,438.56, 2,155.82 and 821.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,438.56 : 2,155.82 = 821.34 : x
2. Step 2: Convert to fraction form
   1,438.56/2,155.82 = 821.34/x
3. Step 3: Cross multiply
   1,438.56x = 2,155.82 × 821.34
4. Step 4: Simplify right side
   1,438.56x = 1,770,657.09
5. Step 5: Solve for x
   x = 1,770,657.09/1,438.56
6. Step 6: Final answer
   x = 1,230.85