Finding the Fourth Proportional to 1,321.98, 1,981.54 and 860.09

Step by Step Solution

1. Step 1: Write the proportion equation
   1,321.98 : 1,981.54 = 860.09 : x
2. Step 2: Convert to fraction form
   1,321.98/1,981.54 = 860.09/x
3. Step 3: Cross multiply
   1,321.98x = 1,981.54 × 860.09
4. Step 4: Simplify right side
   1,321.98x = 1,704,302.74
5. Step 5: Solve for x
   x = 1,704,302.74/1,321.98
6. Step 6: Final answer
   x = 1,289.20