Finding the Fourth Proportional to 12,991.92, 17,930.34 and 7,688.58

Step by Step Solution

1. Step 1: Write the proportion equation
   12,991.92 : 17,930.34 = 7,688.58 : x
2. Step 2: Convert to fraction form
   12,991.92/17,930.34 = 7,688.58/x
3. Step 3: Cross multiply
   12,991.92x = 17,930.34 × 7,688.58
4. Step 4: Simplify right side
   12,991.92x = 137,858,853.52
5. Step 5: Solve for x
   x = 137,858,853.52/12,991.92
6. Step 6: Final answer
   x = 10,611.12