Finding the Fourth Proportional to 2,575.91, 3,864.17 and 820.30

Step by Step Solution

1. Step 1: Write the proportion equation
   2,575.91 : 3,864.17 = 820.30 : x
2. Step 2: Convert to fraction form
   2,575.91/3,864.17 = 820.30/x
3. Step 3: Cross multiply
   2,575.91x = 3,864.17 × 820.30
4. Step 4: Simplify right side
   2,575.91x = 3,169,784.51
5. Step 5: Solve for x
   x = 3,169,784.51/2,575.91
6. Step 6: Final answer
   x = 1,230.55