Finding the Third Proportional to 13,018.50 and 20,139.75

Step by Step Solution

1. Step 1: Write the proportion equation
   13,018.50 : 20,139.75 = 20,139.75 : x
2. Step 2: Convert to fraction form
   13,018.50/20,139.75 = 20,139.75/x
3. Step 3: Cross multiply
   13,018.50x = 20,139.75 × 20,139.75
4. Step 4: Simplify right side
   13,018.50x = 405,609,530.06
5. Step 5: Solve for x
   x = 405,609,530.06/13,018.50
6. Step 6: Final answer
   x = 31,156.40