Finding the Fourth Proportional to 1,440.16, 1,987.36 and 810.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,440.16 : 1,987.36 = 810.72 : x
2. Step 2: Convert to fraction form
   1,440.16/1,987.36 = 810.72/x
3. Step 3: Cross multiply
   1,440.16x = 1,987.36 × 810.72
4. Step 4: Simplify right side
   1,440.16x = 1,611,190.47
5. Step 5: Solve for x
   x = 1,611,190.47/1,440.16
6. Step 6: Final answer
   x = 1,118.76