Finding the Fourth Proportional to 9,139.45, 12,612.35 and 5,160.47

Step by Step Solution

1. Step 1: Write the proportion equation
   9,139.45 : 12,612.35 = 5,160.47 : x
2. Step 2: Convert to fraction form
   9,139.45/12,612.35 = 5,160.47/x
3. Step 3: Cross multiply
   9,139.45x = 12,612.35 × 5,160.47
4. Step 4: Simplify right side
   9,139.45x = 65,085,653.80
5. Step 5: Solve for x
   x = 65,085,653.80/9,139.45
6. Step 6: Final answer
   x = 7,121.40