Finding the Third Proportional to 11,665 and 15,715.50

Step by Step Solution

1. Step 1: Write the proportion equation
   11,665 : 15,715.50 = 15,715.50 : x
2. Step 2: Convert to fraction form
   11,665/15,715.50 = 15,715.50/x
3. Step 3: Cross multiply
   11,665x = 15,715.50 × 15,715.50
4. Step 4: Simplify right side
   11,665x = 246,976,940.25
5. Step 5: Solve for x
   x = 246,976,940.25/11,665
6. Step 6: Final answer
   x = 21,172.48