Finding the Fourth Proportional to 1,253.16, 1,728.72 and 860.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,253.16 : 1,728.72 = 860.40 : x
2. Step 2: Convert to fraction form
   1,253.16/1,728.72 = 860.40/x
3. Step 3: Cross multiply
   1,253.16x = 1,728.72 × 860.40
4. Step 4: Simplify right side
   1,253.16x = 1,487,390.69
5. Step 5: Solve for x
   x = 1,487,390.69/1,253.16
6. Step 6: Final answer
   x = 1,186.91