Finding the Fourth Proportional to 1,380.59, 2,071.58 and 860.46

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.59 : 2,071.58 = 860.46 : x
2. Step 2: Convert to fraction form
   1,380.59/2,071.58 = 860.46/x
3. Step 3: Cross multiply
   1,380.59x = 2,071.58 × 860.46
4. Step 4: Simplify right side
   1,380.59x = 1,782,511.73
5. Step 5: Solve for x
   x = 1,782,511.73/1,380.59
6. Step 6: Final answer
   x = 1,291.12