Finding the Fourth Proportional to 12,655.18, 18,987.69 and 5,257.78

Step by Step Solution

1. Step 1: Write the proportion equation
   12,655.18 : 18,987.69 = 5,257.78 : x
2. Step 2: Convert to fraction form
   12,655.18/18,987.69 = 5,257.78/x
3. Step 3: Cross multiply
   12,655.18x = 18,987.69 × 5,257.78
4. Step 4: Simplify right side
   12,655.18x = 99,833,096.73
5. Step 5: Solve for x
   x = 99,833,096.73/12,655.18
6. Step 6: Final answer
   x = 7,888.71