Finding the Fourth Proportional to 1,978.97, 2,731.12 and 1,139.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,978.97 : 2,731.12 = 1,139.76 : x
2. Step 2: Convert to fraction form
   1,978.97/2,731.12 = 1,139.76/x
3. Step 3: Cross multiply
   1,978.97x = 2,731.12 × 1,139.76
4. Step 4: Simplify right side
   1,978.97x = 3,112,818.48
5. Step 5: Solve for x
   x = 3,112,818.48/1,978.97
6. Step 6: Final answer
   x = 1,572.95