Finding the Fourth Proportional to 1,397.67, 1,928.79 and 808.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,397.67 : 1,928.79 = 808.55 : x
2. Step 2: Convert to fraction form
   1,397.67/1,928.79 = 808.55/x
3. Step 3: Cross multiply
   1,397.67x = 1,928.79 × 808.55
4. Step 4: Simplify right side
   1,397.67x = 1,559,518.47
5. Step 5: Solve for x
   x = 1,559,518.47/1,397.67
6. Step 6: Final answer
   x = 1,115.80