Finding the Fourth Proportional to 1,420.18, 1,960.02 and 860.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,420.18 : 1,960.02 = 860.55 : x
2. Step 2: Convert to fraction form
   1,420.18/1,960.02 = 860.55/x
3. Step 3: Cross multiply
   1,420.18x = 1,960.02 × 860.55
4. Step 4: Simplify right side
   1,420.18x = 1,686,695.21
5. Step 5: Solve for x
   x = 1,686,695.21/1,420.18
6. Step 6: Final answer
   x = 1,187.66