Finding the Fourth Proportional to 8,561.31, 12,842.02 and 2,638.12

Step by Step Solution

1. Step 1: Write the proportion equation
   8,561.31 : 12,842.02 = 2,638.12 : x
2. Step 2: Convert to fraction form
   8,561.31/12,842.02 = 2,638.12/x
3. Step 3: Cross multiply
   8,561.31x = 12,842.02 × 2,638.12
4. Step 4: Simplify right side
   8,561.31x = 33,878,776.61
5. Step 5: Solve for x
   x = 33,878,776.61/8,561.31
6. Step 6: Final answer
   x = 3,957.20