Finding the Fourth Proportional to 20,968.35, 31,214.78 and 20,857.47

Step by Step Solution

1. Step 1: Write the proportion equation
   20,968.35 : 31,214.78 = 20,857.47 : x
2. Step 2: Convert to fraction form
   20,968.35/31,214.78 = 20,857.47/x
3. Step 3: Cross multiply
   20,968.35x = 31,214.78 × 20,857.47
4. Step 4: Simplify right side
   20,968.35x = 651,061,233.12
5. Step 5: Solve for x
   x = 651,061,233.12/20,968.35
6. Step 6: Final answer
   x = 31,049.71