Finding the Fourth Proportional to 10,919.69, 16,379.40 and 3,128.57

Step by Step Solution

1. Step 1: Write the proportion equation
   10,919.69 : 16,379.40 = 3,128.57 : x
2. Step 2: Convert to fraction form
   10,919.69/16,379.40 = 3,128.57/x
3. Step 3: Cross multiply
   10,919.69x = 16,379.40 × 3,128.57
4. Step 4: Simplify right side
   10,919.69x = 51,244,099.46
5. Step 5: Solve for x
   x = 51,244,099.46/10,919.69
6. Step 6: Final answer
   x = 4,692.82