Finding the Fourth Proportional to 21,090.96, 31,626.72 and 12,328.56

Step by Step Solution

1. Step 1: Write the proportion equation
   21,090.96 : 31,626.72 = 12,328.56 : x
2. Step 2: Convert to fraction form
   21,090.96/31,626.72 = 12,328.56/x
3. Step 3: Cross multiply
   21,090.96x = 31,626.72 × 12,328.56
4. Step 4: Simplify right side
   21,090.96x = 389,911,915.12
5. Step 5: Solve for x
   x = 389,911,915.12/21,090.96
6. Step 6: Final answer
   x = 18,487.16