Finding the Fourth Proportional to 1,559.18, 2,151.65 and 860.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,559.18 : 2,151.65 = 860.55 : x
2. Step 2: Convert to fraction form
   1,559.18/2,151.65 = 860.55/x
3. Step 3: Cross multiply
   1,559.18x = 2,151.65 × 860.55
4. Step 4: Simplify right side
   1,559.18x = 1,851,598.10
5. Step 5: Solve for x
   x = 1,851,598.10/1,559.18
6. Step 6: Final answer
   x = 1,187.55