Finding the Fourth Proportional to 1,397.88, 1,928.88 and 808.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,397.88 : 1,928.88 = 808.20 : x
2. Step 2: Convert to fraction form
   1,397.88/1,928.88 = 808.20/x
3. Step 3: Cross multiply
   1,397.88x = 1,928.88 × 808.20
4. Step 4: Simplify right side
   1,397.88x = 1,558,920.82
5. Step 5: Solve for x
   x = 1,558,920.82/1,397.88
6. Step 6: Final answer
   x = 1,115.20