Finding the Fourth Proportional to 21,021.31, 28,993 and 13,468.35

Step by Step Solution

1. Step 1: Write the proportion equation
   21,021.31 : 28,993 = 13,468.35 : x
2. Step 2: Convert to fraction form
   21,021.31/28,993 = 13,468.35/x
3. Step 3: Cross multiply
   21,021.31x = 28,993 × 13,468.35
4. Step 4: Simplify right side
   21,021.31x = 390,487,871.55
5. Step 5: Solve for x
   x = 390,487,871.55/21,021.31
6. Step 6: Final answer
   x = 18,575.81