Finding the Fourth Proportional to 1,239.88, 1,711.56 and 820.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,239.88 : 1,711.56 = 820.42 : x
2. Step 2: Convert to fraction form
   1,239.88/1,711.56 = 820.42/x
3. Step 3: Cross multiply
   1,239.88x = 1,711.56 × 820.42
4. Step 4: Simplify right side
   1,239.88x = 1,404,198.06
5. Step 5: Solve for x
   x = 1,404,198.06/1,239.88
6. Step 6: Final answer
   x = 1,132.53