Finding the Fourth Proportional to 21,059.79, 31,563.15 and 18,421.01

Step by Step Solution

1. Step 1: Write the proportion equation
   21,059.79 : 31,563.15 = 18,421.01 : x
2. Step 2: Convert to fraction form
   21,059.79/31,563.15 = 18,421.01/x
3. Step 3: Cross multiply
   21,059.79x = 31,563.15 × 18,421.01
4. Step 4: Simplify right side
   21,059.79x = 581,425,101.78
5. Step 5: Solve for x
   x = 581,425,101.78/21,059.79
6. Step 6: Final answer
   x = 27,608.31