Finding the Third Proportional to 12,987 and 20,142

Step by Step Solution

1. Step 1: Write the proportion equation
   12,987 : 20,142 = 20,142 : x
2. Step 2: Convert to fraction form
   12,987/20,142 = 20,142/x
3. Step 3: Cross multiply
   12,987x = 20,142 × 20,142
4. Step 4: Simplify right side
   12,987x = 405,700,164
5. Step 5: Solve for x
   x = 405,700,164/12,987
6. Step 6: Final answer
   x = 31,238.94