Finding the Third Proportional to 72 and 139

Step by Step Solution

1. Step 1: Write the proportion equation
   72 : 139 = 139 : x
2. Step 2: Convert to fraction form
   72/139 = 139/x
3. Step 3: Cross multiply
   72x = 139 × 139
4. Step 4: Simplify right side
   72x = 19,321
5. Step 5: Solve for x
   x = 19,321/72
6. Step 6: Final answer
   x = 268.35