Finding the Fourth Proportional to 20,870.64, 28,801.71 and 11,439

Step by Step Solution

1. Step 1: Write the proportion equation
   20,870.64 : 28,801.71 = 11,439 : x
2. Step 2: Convert to fraction form
   20,870.64/28,801.71 = 11,439/x
3. Step 3: Cross multiply
   20,870.64x = 28,801.71 × 11,439
4. Step 4: Simplify right side
   20,870.64x = 329,462,760.69
5. Step 5: Solve for x
   x = 329,462,760.69/20,870.64
6. Step 6: Final answer
   x = 15,785.94