Finding the Fourth Proportional to 9,121.89, 12,587.85 and 5,142.75

Step by Step Solution

1. Step 1: Write the proportion equation
   9,121.89 : 12,587.85 = 5,142.75 : x
2. Step 2: Convert to fraction form
   9,121.89/12,587.85 = 5,142.75/x
3. Step 3: Cross multiply
   9,121.89x = 12,587.85 × 5,142.75
4. Step 4: Simplify right side
   9,121.89x = 64,736,165.59
5. Step 5: Solve for x
   x = 64,736,165.59/9,121.89
6. Step 6: Final answer
   x = 7,096.79