Finding the Third Proportional to 8,570 and 12,987

Step by Step Solution

1. Step 1: Write the proportion equation
   8,570 : 12,987 = 12,987 : x
2. Step 2: Convert to fraction form
   8,570/12,987 = 12,987/x
3. Step 3: Cross multiply
   8,570x = 12,987 × 12,987
4. Step 4: Simplify right side
   8,570x = 168,662,169
5. Step 5: Solve for x
   x = 168,662,169/8,570
6. Step 6: Final answer
   x = 19,680.53