Finding the Fourth Proportional to 1,406.78, 1,942.02 and 817.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,406.78 : 1,942.02 = 817.20 : x
2. Step 2: Convert to fraction form
   1,406.78/1,942.02 = 817.20/x
3. Step 3: Cross multiply
   1,406.78x = 1,942.02 × 817.20
4. Step 4: Simplify right side
   1,406.78x = 1,587,018.74
5. Step 5: Solve for x
   x = 1,587,018.74/1,406.78
6. Step 6: Final answer
   x = 1,128.12