Finding the Fourth Proportional to 12,781.91, 17,638.89 and 7,116.50

Step by Step Solution

1. Step 1: Write the proportion equation
   12,781.91 : 17,638.89 = 7,116.50 : x
2. Step 2: Convert to fraction form
   12,781.91/17,638.89 = 7,116.50/x
3. Step 3: Cross multiply
   12,781.91x = 17,638.89 × 7,116.50
4. Step 4: Simplify right side
   12,781.91x = 125,527,160.69
5. Step 5: Solve for x
   x = 125,527,160.69/12,781.91
6. Step 6: Final answer
   x = 9,820.69