Finding the Fourth Proportional to 10,395.78, 15,580.17 and 7,921.50

Step by Step Solution

1. Step 1: Write the proportion equation
   10,395.78 : 15,580.17 = 7,921.50 : x
2. Step 2: Convert to fraction form
   10,395.78/15,580.17 = 7,921.50/x
3. Step 3: Cross multiply
   10,395.78x = 15,580.17 × 7,921.50
4. Step 4: Simplify right side
   10,395.78x = 123,418,316.66
5. Step 5: Solve for x
   x = 123,418,316.66/10,395.78
6. Step 6: Final answer
   x = 11,871.96