Finding the Fourth Proportional to 1,978.89, 2,730.79 and 1,139.63

Step by Step Solution

1. Step 1: Write the proportion equation
   1,978.89 : 2,730.79 = 1,139.63 : x
2. Step 2: Convert to fraction form
   1,978.89/2,730.79 = 1,139.63/x
3. Step 3: Cross multiply
   1,978.89x = 2,730.79 × 1,139.63
4. Step 4: Simplify right side
   1,978.89x = 3,112,073.70
5. Step 5: Solve for x
   x = 3,112,073.70/1,978.89
6. Step 6: Final answer
   x = 1,572.64