Finding the Fourth Proportional to 1,405.84, 1,939.60 and 816.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,405.84 : 1,939.60 = 816.56 : x
2. Step 2: Convert to fraction form
   1,405.84/1,939.60 = 816.56/x
3. Step 3: Cross multiply
   1,405.84x = 1,939.60 × 816.56
4. Step 4: Simplify right side
   1,405.84x = 1,583,799.78
5. Step 5: Solve for x
   x = 1,583,799.78/1,405.84
6. Step 6: Final answer
   x = 1,126.59