Finding the Fourth Proportional to 12,991.14, 17,931.38 and 7,688.88

Step by Step Solution

1. Step 1: Write the proportion equation
   12,991.14 : 17,931.38 = 7,688.88 : x
2. Step 2: Convert to fraction form
   12,991.14/17,931.38 = 7,688.88/x
3. Step 3: Cross multiply
   12,991.14x = 17,931.38 × 7,688.88
4. Step 4: Simplify right side
   12,991.14x = 137,872,190.61
5. Step 5: Solve for x
   x = 137,872,190.61/12,991.14
6. Step 6: Final answer
   x = 10,612.79