Finding the Fourth Proportional to 1,392.39, 2,089.59 and 931.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,392.39 : 2,089.59 = 931.05 : x
2. Step 2: Convert to fraction form
   1,392.39/2,089.59 = 931.05/x
3. Step 3: Cross multiply
   1,392.39x = 2,089.59 × 931.05
4. Step 4: Simplify right side
   1,392.39x = 1,945,512.77
5. Step 5: Solve for x
   x = 1,945,512.77/1,392.39
6. Step 6: Final answer
   x = 1,397.25