Finding the Third Proportional to 90.49 and 139.85

Step by Step Solution

1. Step 1: Write the proportion equation
   90.49 : 139.85 = 139.85 : x
2. Step 2: Convert to fraction form
   90.49/139.85 = 139.85/x
3. Step 3: Cross multiply
   90.49x = 139.85 × 139.85
4. Step 4: Simplify right side
   90.49x = 19,558.46
5. Step 5: Solve for x
   x = 19,558.46/90.49
6. Step 6: Final answer
   x = 216.13