Finding the Fourth Proportional to 12,721.30, 17,555.76 and 7,686.42

Step by Step Solution

1. Step 1: Write the proportion equation
   12,721.30 : 17,555.76 = 7,686.42 : x
2. Step 2: Convert to fraction form
   12,721.30/17,555.76 = 7,686.42/x
3. Step 3: Cross multiply
   12,721.30x = 17,555.76 × 7,686.42
4. Step 4: Simplify right side
   12,721.30x = 134,940,944.78
5. Step 5: Solve for x
   x = 134,940,944.78/12,721.30
6. Step 6: Final answer
   x = 10,607.48