Finding the Fourth Proportional to 8,642.50, 12,891.91 and 8,499.81

Step by Step Solution

1. Step 1: Write the proportion equation
   8,642.50 : 12,891.91 = 8,499.81 : x
2. Step 2: Convert to fraction form
   8,642.50/12,891.91 = 8,499.81/x
3. Step 3: Cross multiply
   8,642.50x = 12,891.91 × 8,499.81
4. Step 4: Simplify right side
   8,642.50x = 109,578,785.54
5. Step 5: Solve for x
   x = 109,578,785.54/8,642.50
6. Step 6: Final answer
   x = 12,679.06