Finding the Fourth Proportional to 9,321.78, 12,864.06 and 5,130

Step by Step Solution

1. Step 1: Write the proportion equation
   9,321.78 : 12,864.06 = 5,130 : x
2. Step 2: Convert to fraction form
   9,321.78/12,864.06 = 5,130/x
3. Step 3: Cross multiply
   9,321.78x = 12,864.06 × 5,130
4. Step 4: Simplify right side
   9,321.78x = 65,992,627.80
5. Step 5: Solve for x
   x = 65,992,627.80/9,321.78
6. Step 6: Final answer
   x = 7,079.40