Finding the Fourth Proportional to 21,139.58, 31,686.48 and 13,749.34

Step by Step Solution

1. Step 1: Write the proportion equation
   21,139.58 : 31,686.48 = 13,749.34 : x
2. Step 2: Convert to fraction form
   21,139.58/31,686.48 = 13,749.34/x
3. Step 3: Cross multiply
   21,139.58x = 31,686.48 × 13,749.34
4. Step 4: Simplify right side
   21,139.58x = 435,668,186.92
5. Step 5: Solve for x
   x = 435,668,186.92/21,139.58
6. Step 6: Final answer
   x = 20,609.12