Finding the Fourth Proportional to 1,385.77, 1,910.66 and 860.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,385.77 : 1,910.66 = 860.89 : x
2. Step 2: Convert to fraction form
   1,385.77/1,910.66 = 860.89/x
3. Step 3: Cross multiply
   1,385.77x = 1,910.66 × 860.89
4. Step 4: Simplify right side
   1,385.77x = 1,644,872.63
5. Step 5: Solve for x
   x = 1,644,872.63/1,385.77
6. Step 6: Final answer
   x = 1,186.97