Finding the Fourth Proportional to 12,213.61, 18,321.72 and 3,891.67

Step by Step Solution

1. Step 1: Write the proportion equation
   12,213.61 : 18,321.72 = 3,891.67 : x
2. Step 2: Convert to fraction form
   12,213.61/18,321.72 = 3,891.67/x
3. Step 3: Cross multiply
   12,213.61x = 18,321.72 × 3,891.67
4. Step 4: Simplify right side
   12,213.61x = 71,302,090.15
5. Step 5: Solve for x
   x = 71,302,090.15/12,213.61
6. Step 6: Final answer
   x = 5,837.92