Finding the Fourth Proportional to 21,087.94, 31,566.28 and 13,280.34

Step by Step Solution

1. Step 1: Write the proportion equation
   21,087.94 : 31,566.28 = 13,280.34 : x
2. Step 2: Convert to fraction form
   21,087.94/31,566.28 = 13,280.34/x
3. Step 3: Cross multiply
   21,087.94x = 31,566.28 × 13,280.34
4. Step 4: Simplify right side
   21,087.94x = 419,210,930.94
5. Step 5: Solve for x
   x = 419,210,930.94/21,087.94
6. Step 6: Final answer
   x = 19,879.18