Finding the Third Proportional to 8,494 and 12,991

Step by Step Solution

1. Step 1: Write the proportion equation
   8,494 : 12,991 = 12,991 : x
2. Step 2: Convert to fraction form
   8,494/12,991 = 12,991/x
3. Step 3: Cross multiply
   8,494x = 12,991 × 12,991
4. Step 4: Simplify right side
   8,494x = 168,766,081
5. Step 5: Solve for x
   x = 168,766,081/8,494
6. Step 6: Final answer
   x = 19,868.86