Finding the Fourth Proportional to 10,978.54, 15,157.53 and 8,456.20

Step by Step Solution

1. Step 1: Write the proportion equation
   10,978.54 : 15,157.53 = 8,456.20 : x
2. Step 2: Convert to fraction form
   10,978.54/15,157.53 = 8,456.20/x
3. Step 3: Cross multiply
   10,978.54x = 15,157.53 × 8,456.20
4. Step 4: Simplify right side
   10,978.54x = 128,175,067.29
5. Step 5: Solve for x
   x = 128,175,067.29/10,978.54
6. Step 6: Final answer
   x = 11,675.06