Finding the Fourth Proportional to 12,720.72, 17,561.20 and 9,881.76

Step by Step Solution

1. Step 1: Write the proportion equation
   12,720.72 : 17,561.20 = 9,881.76 : x
2. Step 2: Convert to fraction form
   12,720.72/17,561.20 = 9,881.76/x
3. Step 3: Cross multiply
   12,720.72x = 17,561.20 × 9,881.76
4. Step 4: Simplify right side
   12,720.72x = 173,535,563.71
5. Step 5: Solve for x
   x = 173,535,563.71/12,720.72
6. Step 6: Final answer
   x = 13,641.96