Finding the Fourth Proportional to 12,978.32, 17,911.42 and 7,945.86

Step by Step Solution

1. Step 1: Write the proportion equation
   12,978.32 : 17,911.42 = 7,945.86 : x
2. Step 2: Convert to fraction form
   12,978.32/17,911.42 = 7,945.86/x
3. Step 3: Cross multiply
   12,978.32x = 17,911.42 × 7,945.86
4. Step 4: Simplify right side
   12,978.32x = 142,321,635.72
5. Step 5: Solve for x
   x = 142,321,635.72/12,978.32
6. Step 6: Final answer
   x = 10,966.11