Finding the Third Proportional to 11.50 and 21.31

Step by Step Solution

1. Step 1: Write the proportion equation
   11.50 : 21.31 = 21.31 : x
2. Step 2: Convert to fraction form
   11.50/21.31 = 21.31/x
3. Step 3: Cross multiply
   11.50x = 21.31 × 21.31
4. Step 4: Simplify right side
   11.50x = 454.22
5. Step 5: Solve for x
   x = 454.22/11.50
6. Step 6: Final answer
   x = 39.50