Finding the Fourth Proportional to 11,978.52, 17,971.32 and 6,139.20

Step by Step Solution

1. Step 1: Write the proportion equation
   11,978.52 : 17,971.32 = 6,139.20 : x
2. Step 2: Convert to fraction form
   11,978.52/17,971.32 = 6,139.20/x
3. Step 3: Cross multiply
   11,978.52x = 17,971.32 × 6,139.20
4. Step 4: Simplify right side
   11,978.52x = 110,329,527.74
5. Step 5: Solve for x
   x = 110,329,527.74/11,978.52
6. Step 6: Final answer
   x = 9,210.61