Finding the Fourth Proportional to 1,407.15, 2,112.85 and 861.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,407.15 : 2,112.85 = 861.61 : x
2. Step 2: Convert to fraction form
   1,407.15/2,112.85 = 861.61/x
3. Step 3: Cross multiply
   1,407.15x = 2,112.85 × 861.61
4. Step 4: Simplify right side
   1,407.15x = 1,820,452.69
5. Step 5: Solve for x
   x = 1,820,452.69/1,407.15
6. Step 6: Final answer
   x = 1,293.72