Finding the Third Proportional to 21.56 and 42.56

Step by Step Solution

1. Step 1: Write the proportion equation
   21.56 : 42.56 = 42.56 : x
2. Step 2: Convert to fraction form
   21.56/42.56 = 42.56/x
3. Step 3: Cross multiply
   21.56x = 42.56 × 42.56
4. Step 4: Simplify right side
   21.56x = 1,811.57
5. Step 5: Solve for x
   x = 1,811.57/21.56
6. Step 6: Final answer
   x = 84.01