Finding the Fourth Proportional to 2,287.15, 3,156.25 and 1,239.20

Step by Step Solution

1. Step 1: Write the proportion equation
   2,287.15 : 3,156.25 = 1,239.20 : x
2. Step 2: Convert to fraction form
   2,287.15/3,156.25 = 1,239.20/x
3. Step 3: Cross multiply
   2,287.15x = 3,156.25 × 1,239.20
4. Step 4: Simplify right side
   2,287.15x = 3,911,218.80
5. Step 5: Solve for x
   x = 3,911,218.80/2,287.15
6. Step 6: Final answer
   x = 1,710.09