Finding the Fourth Proportional to 21,109.68, 31,659.12 and 7,958.16

Step by Step Solution

1. Step 1: Write the proportion equation
   21,109.68 : 31,659.12 = 7,958.16 : x
2. Step 2: Convert to fraction form
   21,109.68/31,659.12 = 7,958.16/x
3. Step 3: Cross multiply
   21,109.68x = 31,659.12 × 7,958.16
4. Step 4: Simplify right side
   21,109.68x = 251,948,342.42
5. Step 5: Solve for x
   x = 251,948,342.42/21,109.68
6. Step 6: Final answer
   x = 11,935.20