Finding the Fourth Proportional to 21,078.72, 31,613.76 and 7,930.80

Step by Step Solution

1. Step 1: Write the proportion equation
   21,078.72 : 31,613.76 = 7,930.80 : x
2. Step 2: Convert to fraction form
   21,078.72/31,613.76 = 7,930.80/x
3. Step 3: Cross multiply
   21,078.72x = 31,613.76 × 7,930.80
4. Step 4: Simplify right side
   21,078.72x = 250,722,407.81
5. Step 5: Solve for x
   x = 250,722,407.81/21,078.72
6. Step 6: Final answer
   x = 11,894.57