Finding the Third Proportional to 11,991 and 13,215

Step by Step Solution

1. Step 1: Write the proportion equation
   11,991 : 13,215 = 13,215 : x
2. Step 2: Convert to fraction form
   11,991/13,215 = 13,215/x
3. Step 3: Cross multiply
   11,991x = 13,215 × 13,215
4. Step 4: Simplify right side
   11,991x = 174,636,225
5. Step 5: Solve for x
   x = 174,636,225/11,991
6. Step 6: Final answer
   x = 14,563.94