Finding the Fourth Proportional to 13,728.22, 20,415.72 and 13,290.82

Step by Step Solution

1. Step 1: Write the proportion equation
   13,728.22 : 20,415.72 = 13,290.82 : x
2. Step 2: Convert to fraction form
   13,728.22/20,415.72 = 13,290.82/x
3. Step 3: Cross multiply
   13,728.22x = 20,415.72 × 13,290.82
4. Step 4: Simplify right side
   13,728.22x = 271,341,659.69
5. Step 5: Solve for x
   x = 271,341,659.69/13,728.22
6. Step 6: Final answer
   x = 19,765.25