Finding the Fourth Proportional to 21,116.72, 31,678.32 and 7,968.80

Step by Step Solution

1. Step 1: Write the proportion equation
   21,116.72 : 31,678.32 = 7,968.80 : x
2. Step 2: Convert to fraction form
   21,116.72/31,678.32 = 7,968.80/x
3. Step 3: Cross multiply
   21,116.72x = 31,678.32 × 7,968.80
4. Step 4: Simplify right side
   21,116.72x = 252,438,196.42
5. Step 5: Solve for x
   x = 252,438,196.42/21,116.72
6. Step 6: Final answer
   x = 11,954.42