Finding the Third Proportional to 31.99 and 67.57

Step by Step Solution

1. Step 1: Write the proportion equation
   31.99 : 67.57 = 67.57 : x
2. Step 2: Convert to fraction form
   31.99/67.57 = 67.57/x
3. Step 3: Cross multiply
   31.99x = 67.57 × 67.57
4. Step 4: Simplify right side
   31.99x = 4,565.75
5. Step 5: Solve for x
   x = 4,565.75/31.99
6. Step 6: Final answer
   x = 142.71