Finding the Third Proportional to 21.56 and 43.31

Step by Step Solution

1. Step 1: Write the proportion equation
   21.56 : 43.31 = 43.31 : x
2. Step 2: Convert to fraction form
   21.56/43.31 = 43.31/x
3. Step 3: Cross multiply
   21.56x = 43.31 × 43.31
4. Step 4: Simplify right side
   21.56x = 1,875.97
5. Step 5: Solve for x
   x = 1,875.97/21.56
6. Step 6: Final answer
   x = 87.00