Finding the Fourth Proportional to 1,007.25, 1,388.79 and 820.35

Step by Step Solution

1. Step 1: Write the proportion equation
   1,007.25 : 1,388.79 = 820.35 : x
2. Step 2: Convert to fraction form
   1,007.25/1,388.79 = 820.35/x
3. Step 3: Cross multiply
   1,007.25x = 1,388.79 × 820.35
4. Step 4: Simplify right side
   1,007.25x = 1,139,293.88
5. Step 5: Solve for x
   x = 1,139,293.88/1,007.25
6. Step 6: Final answer
   x = 1,131.09