Finding the Fourth Proportional to 1,078.71, 1,619.55 and 859.47

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.71 : 1,619.55 = 859.47 : x
2. Step 2: Convert to fraction form
   1,078.71/1,619.55 = 859.47/x
3. Step 3: Cross multiply
   1,078.71x = 1,619.55 × 859.47
4. Step 4: Simplify right side
   1,078.71x = 1,391,954.64
5. Step 5: Solve for x
   x = 1,391,954.64/1,078.71
6. Step 6: Final answer
   x = 1,290.39