Finding the Fourth Proportional to 13,978.20, 20,932.72 and 8,117.04

Step by Step Solution

1. Step 1: Write the proportion equation
   13,978.20 : 20,932.72 = 8,117.04 : x
2. Step 2: Convert to fraction form
   13,978.20/20,932.72 = 8,117.04/x
3. Step 3: Cross multiply
   13,978.20x = 20,932.72 × 8,117.04
4. Step 4: Simplify right side
   13,978.20x = 169,911,725.55
5. Step 5: Solve for x
   x = 169,911,725.55/13,978.20
6. Step 6: Final answer
   x = 12,155.48