Finding the Fourth Proportional to 10,665.45, 15,991.31 and 4,429.76

Step by Step Solution

1. Step 1: Write the proportion equation
   10,665.45 : 15,991.31 = 4,429.76 : x
2. Step 2: Convert to fraction form
   10,665.45/15,991.31 = 4,429.76/x
3. Step 3: Cross multiply
   10,665.45x = 15,991.31 × 4,429.76
4. Step 4: Simplify right side
   10,665.45x = 70,837,585.43
5. Step 5: Solve for x
   x = 70,837,585.43/10,665.45
6. Step 6: Final answer
   x = 6,641.78