Finding the Fourth Proportional to 9,211.61, 12,711.31 and 5,178.21

Step by Step Solution

1. Step 1: Write the proportion equation
   9,211.61 : 12,711.31 = 5,178.21 : x
2. Step 2: Convert to fraction form
   9,211.61/12,711.31 = 5,178.21/x
3. Step 3: Cross multiply
   9,211.61x = 12,711.31 × 5,178.21
4. Step 4: Simplify right side
   9,211.61x = 65,821,819.61
5. Step 5: Solve for x
   x = 65,821,819.61/9,211.61
6. Step 6: Final answer
   x = 7,145.53