Finding the Fourth Proportional to 1,431.80, 1,975.86 and 810.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,431.80 : 1,975.86 = 810.76 : x
2. Step 2: Convert to fraction form
   1,431.80/1,975.86 = 810.76/x
3. Step 3: Cross multiply
   1,431.80x = 1,975.86 × 810.76
4. Step 4: Simplify right side
   1,431.80x = 1,601,948.25
5. Step 5: Solve for x
   x = 1,601,948.25/1,431.80
6. Step 6: Final answer
   x = 1,118.84