Finding the Fourth Proportional to 8,109.99, 12,168.78 and 7,978.95

Step by Step Solution

1. Step 1: Write the proportion equation
   8,109.99 : 12,168.78 = 7,978.95 : x
2. Step 2: Convert to fraction form
   8,109.99/12,168.78 = 7,978.95/x
3. Step 3: Cross multiply
   8,109.99x = 12,168.78 × 7,978.95
4. Step 4: Simplify right side
   8,109.99x = 97,094,087.18
5. Step 5: Solve for x
   x = 97,094,087.18/8,109.99
6. Step 6: Final answer
   x = 11,972.16