Finding the Fourth Proportional to 15,854.16, 21,878.52 and 9,139.80

Step by Step Solution

1. Step 1: Write the proportion equation
   15,854.16 : 21,878.52 = 9,139.80 : x
2. Step 2: Convert to fraction form
   15,854.16/21,878.52 = 9,139.80/x
3. Step 3: Cross multiply
   15,854.16x = 21,878.52 × 9,139.80
4. Step 4: Simplify right side
   15,854.16x = 199,965,297.10
5. Step 5: Solve for x
   x = 199,965,297.10/15,854.16
6. Step 6: Final answer
   x = 12,612.80