Finding the Third Proportional to 21.75 and 41.31

Step by Step Solution

1. Step 1: Write the proportion equation
   21.75 : 41.31 = 41.31 : x
2. Step 2: Convert to fraction form
   21.75/41.31 = 41.31/x
3. Step 3: Cross multiply
   21.75x = 41.31 × 41.31
4. Step 4: Simplify right side
   21.75x = 1,706.72
5. Step 5: Solve for x
   x = 1,706.72/21.75
6. Step 6: Final answer
   x = 78.47