Finding the Third Proportional to 90.88 and 139.06

Step by Step Solution

1. Step 1: Write the proportion equation
   90.88 : 139.06 = 139.06 : x
2. Step 2: Convert to fraction form
   90.88/139.06 = 139.06/x
3. Step 3: Cross multiply
   90.88x = 139.06 × 139.06
4. Step 4: Simplify right side
   90.88x = 19,338.38
5. Step 5: Solve for x
   x = 19,338.38/90.88
6. Step 6: Final answer
   x = 212.80