Finding the Fourth Proportional to 1,397.72, 1,928.57 and 808.13

Step by Step Solution

1. Step 1: Write the proportion equation
   1,397.72 : 1,928.57 = 808.13 : x
2. Step 2: Convert to fraction form
   1,397.72/1,928.57 = 808.13/x
3. Step 3: Cross multiply
   1,397.72x = 1,928.57 × 808.13
4. Step 4: Simplify right side
   1,397.72x = 1,558,521.59
5. Step 5: Solve for x
   x = 1,558,521.59/1,397.72
6. Step 6: Final answer
   x = 1,115.05