Finding the Third Proportional to 8,172 and 12,987

Step by Step Solution

1. Step 1: Write the proportion equation
   8,172 : 12,987 = 12,987 : x
2. Step 2: Convert to fraction form
   8,172/12,987 = 12,987/x
3. Step 3: Cross multiply
   8,172x = 12,987 × 12,987
4. Step 4: Simplify right side
   8,172x = 168,662,169
5. Step 5: Solve for x
   x = 168,662,169/8,172
6. Step 6: Final answer
   x = 20,639.03