Finding the Third Proportional to 91.50 and 139.50

Step by Step Solution

1. Step 1: Write the proportion equation
   91.50 : 139.50 = 139.50 : x
2. Step 2: Convert to fraction form
   91.50/139.50 = 139.50/x
3. Step 3: Cross multiply
   91.50x = 139.50 × 139.50
4. Step 4: Simplify right side
   91.50x = 19,460.25
5. Step 5: Solve for x
   x = 19,460.25/91.50
6. Step 6: Final answer
   x = 212.68