Finding the Third Proportional to 13,142 and 20,405

Step by Step Solution

1. Step 1: Write the proportion equation
   13,142 : 20,405 = 20,405 : x
2. Step 2: Convert to fraction form
   13,142/20,405 = 20,405/x
3. Step 3: Cross multiply
   13,142x = 20,405 × 20,405
4. Step 4: Simplify right side
   13,142x = 416,364,025
5. Step 5: Solve for x
   x = 416,364,025/13,142
6. Step 6: Final answer
   x = 31,681.94