Finding the Fourth Proportional to 10,979.80, 16,471.82 and 7,991.96

Step by Step Solution

1. Step 1: Write the proportion equation
   10,979.80 : 16,471.82 = 7,991.96 : x
2. Step 2: Convert to fraction form
   10,979.80/16,471.82 = 7,991.96/x
3. Step 3: Cross multiply
   10,979.80x = 16,471.82 × 7,991.96
4. Step 4: Simplify right side
   10,979.80x = 131,642,126.57
5. Step 5: Solve for x
   x = 131,642,126.57/10,979.80
6. Step 6: Final answer
   x = 11,989.48