Finding the Fourth Proportional to 9,990.43, 14,981.28 and 5,309.31

Step by Step Solution

1. Step 1: Write the proportion equation
   9,990.43 : 14,981.28 = 5,309.31 : x
2. Step 2: Convert to fraction form
   9,990.43/14,981.28 = 5,309.31/x
3. Step 3: Cross multiply
   9,990.43x = 14,981.28 × 5,309.31
4. Step 4: Simplify right side
   9,990.43x = 79,540,259.72
5. Step 5: Solve for x
   x = 79,540,259.72/9,990.43
6. Step 6: Final answer
   x = 7,961.65