Finding the Fourth Proportional to 13,021.12, 17,978.06 and 8,311.78

Step by Step Solution

1. Step 1: Write the proportion equation
   13,021.12 : 17,978.06 = 8,311.78 : x
2. Step 2: Convert to fraction form
   13,021.12/17,978.06 = 8,311.78/x
3. Step 3: Cross multiply
   13,021.12x = 17,978.06 × 8,311.78
4. Step 4: Simplify right side
   13,021.12x = 149,429,679.55
5. Step 5: Solve for x
   x = 149,429,679.55/13,021.12
6. Step 6: Final answer
   x = 11,475.95