Finding the Third Proportional to 89.72 and 138.09

Step by Step Solution

1. Step 1: Write the proportion equation
   89.72 : 138.09 = 138.09 : x
2. Step 2: Convert to fraction form
   89.72/138.09 = 138.09/x
3. Step 3: Cross multiply
   89.72x = 138.09 × 138.09
4. Step 4: Simplify right side
   89.72x = 19,069.88
5. Step 5: Solve for x
   x = 19,069.88/89.72
6. Step 6: Final answer
   x = 212.55