Finding the Fourth Proportional to 1,427.88, 1,969.72 and 860.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,427.88 : 1,969.72 = 860.40 : x
2. Step 2: Convert to fraction form
   1,427.88/1,969.72 = 860.40/x
3. Step 3: Cross multiply
   1,427.88x = 1,969.72 × 860.40
4. Step 4: Simplify right side
   1,427.88x = 1,694,747.09
5. Step 5: Solve for x
   x = 1,694,747.09/1,427.88
6. Step 6: Final answer
   x = 1,186.90