Finding the Third Proportional to 90.50 and 139.75

Step by Step Solution

1. Step 1: Write the proportion equation
   90.50 : 139.75 = 139.75 : x
2. Step 2: Convert to fraction form
   90.50/139.75 = 139.75/x
3. Step 3: Cross multiply
   90.50x = 139.75 × 139.75
4. Step 4: Simplify right side
   90.50x = 19,530.06
5. Step 5: Solve for x
   x = 19,530.06/90.50
6. Step 6: Final answer
   x = 215.80