Finding the Fourth Proportional to 1,436.78, 1,982.80 and 815.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,436.78 : 1,982.80 = 815.78 : x
2. Step 2: Convert to fraction form
   1,436.78/1,982.80 = 815.78/x
3. Step 3: Cross multiply
   1,436.78x = 1,982.80 × 815.78
4. Step 4: Simplify right side
   1,436.78x = 1,617,528.58
5. Step 5: Solve for x
   x = 1,617,528.58/1,436.78
6. Step 6: Final answer
   x = 1,125.80