Finding the Fourth Proportional to 1,978.91, 2,730.59 and 1,139.65

Step by Step Solution

1. Step 1: Write the proportion equation
   1,978.91 : 2,730.59 = 1,139.65 : x
2. Step 2: Convert to fraction form
   1,978.91/2,730.59 = 1,139.65/x
3. Step 3: Cross multiply
   1,978.91x = 2,730.59 × 1,139.65
4. Step 4: Simplify right side
   1,978.91x = 3,111,930.41
5. Step 5: Solve for x
   x = 3,111,930.41/1,978.91
6. Step 6: Final answer
   x = 1,572.54