Finding the Fourth Proportional to 1,385.96, 1,912.29 and 861.62

Step by Step Solution

1. Step 1: Write the proportion equation
   1,385.96 : 1,912.29 = 861.62 : x
2. Step 2: Convert to fraction form
   1,385.96/1,912.29 = 861.62/x
3. Step 3: Cross multiply
   1,385.96x = 1,912.29 × 861.62
4. Step 4: Simplify right side
   1,385.96x = 1,647,667.31
5. Step 5: Solve for x
   x = 1,647,667.31/1,385.96
6. Step 6: Final answer
   x = 1,188.83