Finding the Fourth Proportional to 1,405.86, 1,939.92 and 816.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,405.86 : 1,939.92 = 816.30 : x
2. Step 2: Convert to fraction form
   1,405.86/1,939.92 = 816.30/x
3. Step 3: Cross multiply
   1,405.86x = 1,939.92 × 816.30
4. Step 4: Simplify right side
   1,405.86x = 1,583,556.70
5. Step 5: Solve for x
   x = 1,583,556.70/1,405.86
6. Step 6: Final answer
   x = 1,126.40