Finding the Third Proportional to 85.50 and 121.50

Step by Step Solution

1. Step 1: Write the proportion equation
   85.50 : 121.50 = 121.50 : x
2. Step 2: Convert to fraction form
   85.50/121.50 = 121.50/x
3. Step 3: Cross multiply
   85.50x = 121.50 × 121.50
4. Step 4: Simplify right side
   85.50x = 14,762.25
5. Step 5: Solve for x
   x = 14,762.25/85.50
6. Step 6: Final answer
   x = 172.66