Finding the Third Proportional to 172.25 and 398.50

Step by Step Solution

1. Step 1: Write the proportion equation
   172.25 : 398.50 = 398.50 : x
2. Step 2: Convert to fraction form
   172.25/398.50 = 398.50/x
3. Step 3: Cross multiply
   172.25x = 398.50 × 398.50
4. Step 4: Simplify right side
   172.25x = 158,802.25
5. Step 5: Solve for x
   x = 158,802.25/172.25
6. Step 6: Final answer
   x = 921.93