Finding the Fourth Proportional to 1,039.72, 1,557.42 and 808.36

Step by Step Solution

1. Step 1: Write the proportion equation
   1,039.72 : 1,557.42 = 808.36 : x
2. Step 2: Convert to fraction form
   1,039.72/1,557.42 = 808.36/x
3. Step 3: Cross multiply
   1,039.72x = 1,557.42 × 808.36
4. Step 4: Simplify right side
   1,039.72x = 1,258,956.03
5. Step 5: Solve for x
   x = 1,258,956.03/1,039.72
6. Step 6: Final answer
   x = 1,210.86