Finding the Fourth Proportional to 1,185.50, 1,778.67 and 860.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,185.50 : 1,778.67 = 860.30 : x
2. Step 2: Convert to fraction form
   1,185.50/1,778.67 = 860.30/x
3. Step 3: Cross multiply
   1,185.50x = 1,778.67 × 860.30
4. Step 4: Simplify right side
   1,185.50x = 1,530,189.80
5. Step 5: Solve for x
   x = 1,530,189.80/1,185.50
6. Step 6: Final answer
   x = 1,290.75