Finding the Fourth Proportional to 1,398.45, 1,929.33 and 808.77

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.45 : 1,929.33 = 808.77 : x
2. Step 2: Convert to fraction form
   1,398.45/1,929.33 = 808.77/x
3. Step 3: Cross multiply
   1,398.45x = 1,929.33 × 808.77
4. Step 4: Simplify right side
   1,398.45x = 1,560,384.22
5. Step 5: Solve for x
   x = 1,560,384.22/1,398.45
6. Step 6: Final answer
   x = 1,115.80