Finding the Fourth Proportional to 13,458.01, 20,155.71 and 12,990.82

Step by Step Solution

1. Step 1: Write the proportion equation
   13,458.01 : 20,155.71 = 12,990.82 : x
2. Step 2: Convert to fraction form
   13,458.01/20,155.71 = 12,990.82/x
3. Step 3: Cross multiply
   13,458.01x = 20,155.71 × 12,990.82
4. Step 4: Simplify right side
   13,458.01x = 261,839,200.58
5. Step 5: Solve for x
   x = 261,839,200.58/13,458.01
6. Step 6: Final answer
   x = 19,456.01