Finding the Third Proportional to 171.56 and 338.91

Step by Step Solution

1. Step 1: Write the proportion equation
   171.56 : 338.91 = 338.91 : x
2. Step 2: Convert to fraction form
   171.56/338.91 = 338.91/x
3. Step 3: Cross multiply
   171.56x = 338.91 × 338.91
4. Step 4: Simplify right side
   171.56x = 114,857.45
5. Step 5: Solve for x
   x = 114,857.45/171.56
6. Step 6: Final answer
   x = 669.48