Finding the Fourth Proportional to 15,870.40, 21,900.31 and 9,155.63

Step by Step Solution

1. Step 1: Write the proportion equation
   15,870.40 : 21,900.31 = 9,155.63 : x
2. Step 2: Convert to fraction form
   15,870.40/21,900.31 = 9,155.63/x
3. Step 3: Cross multiply
   15,870.40x = 21,900.31 × 9,155.63
4. Step 4: Simplify right side
   15,870.40x = 200,511,119.31
5. Step 5: Solve for x
   x = 200,511,119.31/15,870.40
6. Step 6: Final answer
   x = 12,634.28