Finding the Fourth Proportional to 1,439.89, 1,987.12 and 810.38

Step by Step Solution

1. Step 1: Write the proportion equation
   1,439.89 : 1,987.12 = 810.38 : x
2. Step 2: Convert to fraction form
   1,439.89/1,987.12 = 810.38/x
3. Step 3: Cross multiply
   1,439.89x = 1,987.12 × 810.38
4. Step 4: Simplify right side
   1,439.89x = 1,610,323.73
5. Step 5: Solve for x
   x = 1,610,323.73/1,439.89
6. Step 6: Final answer
   x = 1,118.37