Finding the Fourth Proportional to 7,139.12, 10,708.60 and 3,978.56

Step by Step Solution

1. Step 1: Write the proportion equation
   7,139.12 : 10,708.60 = 3,978.56 : x
2. Step 2: Convert to fraction form
   7,139.12/10,708.60 = 3,978.56/x
3. Step 3: Cross multiply
   7,139.12x = 10,708.60 × 3,978.56
4. Step 4: Simplify right side
   7,139.12x = 42,604,807.62
5. Step 5: Solve for x
   x = 42,604,807.62/7,139.12
6. Step 6: Final answer
   x = 5,967.80