Finding the Fourth Proportional to 21,030.42, 31,373.28 and 20,458.34

Step by Step Solution

1. Step 1: Write the proportion equation
   21,030.42 : 31,373.28 = 20,458.34 : x
2. Step 2: Convert to fraction form
   21,030.42/31,373.28 = 20,458.34/x
3. Step 3: Cross multiply
   21,030.42x = 31,373.28 × 20,458.34
4. Step 4: Simplify right side
   21,030.42x = 641,845,229.16
5. Step 5: Solve for x
   x = 641,845,229.16/21,030.42
6. Step 6: Final answer
   x = 30,519.85