Finding the Third Proportional to 20.57 and 42.08

Step by Step Solution

1. Step 1: Write the proportion equation
   20.57 : 42.08 = 42.08 : x
2. Step 2: Convert to fraction form
   20.57/42.08 = 42.08/x
3. Step 3: Cross multiply
   20.57x = 42.08 × 42.08
4. Step 4: Simplify right side
   20.57x = 1,770.90
5. Step 5: Solve for x
   x = 1,770.90/20.57
6. Step 6: Final answer
   x = 86.11