Finding the Fourth Proportional to 13,644.63, 18,826.76 and 7,978.28

Step by Step Solution

1. Step 1: Write the proportion equation
   13,644.63 : 18,826.76 = 7,978.28 : x
2. Step 2: Convert to fraction form
   13,644.63/18,826.76 = 7,978.28/x
3. Step 3: Cross multiply
   13,644.63x = 18,826.76 × 7,978.28
4. Step 4: Simplify right side
   13,644.63x = 150,205,088.58
5. Step 5: Solve for x
   x = 150,205,088.58/13,644.63
6. Step 6: Final answer
   x = 11,008.37