Finding the Fourth Proportional to 1,440.21, 1,987.47 and 810.69

Step by Step Solution

1. Step 1: Write the proportion equation
   1,440.21 : 1,987.47 = 810.69 : x
2. Step 2: Convert to fraction form
   1,440.21/1,987.47 = 810.69/x
3. Step 3: Cross multiply
   1,440.21x = 1,987.47 × 810.69
4. Step 4: Simplify right side
   1,440.21x = 1,611,222.05
5. Step 5: Solve for x
   x = 1,611,222.05/1,440.21
6. Step 6: Final answer
   x = 1,118.74