Finding the Fourth Proportional to 1,398.89, 1,930.78 and 926.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.89 : 1,930.78 = 926.81 : x
2. Step 2: Convert to fraction form
   1,398.89/1,930.78 = 926.81/x
3. Step 3: Cross multiply
   1,398.89x = 1,930.78 × 926.81
4. Step 4: Simplify right side
   1,398.89x = 1,789,456.56
5. Step 5: Solve for x
   x = 1,789,456.56/1,398.89
6. Step 6: Final answer
   x = 1,279.20