Finding the Fourth Proportional to 1,385.90, 1,912.38 and 826.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,385.90 : 1,912.38 = 826.40 : x
2. Step 2: Convert to fraction form
   1,385.90/1,912.38 = 826.40/x
3. Step 3: Cross multiply
   1,385.90x = 1,912.38 × 826.40
4. Step 4: Simplify right side
   1,385.90x = 1,580,390.83
5. Step 5: Solve for x
   x = 1,580,390.83/1,385.90
6. Step 6: Final answer
   x = 1,140.34