Finding the Fourth Proportional to 1,380.69, 1,905.37 and 821.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.69 : 1,905.37 = 821.18 : x
2. Step 2: Convert to fraction form
   1,380.69/1,905.37 = 821.18/x
3. Step 3: Cross multiply
   1,380.69x = 1,905.37 × 821.18
4. Step 4: Simplify right side
   1,380.69x = 1,564,654.45
5. Step 5: Solve for x
   x = 1,564,654.45/1,380.69
6. Step 6: Final answer
   x = 1,133.24