Finding the Third Proportional to 489.50 and 561.50

Step by Step Solution

1. Step 1: Write the proportion equation
   489.50 : 561.50 = 561.50 : x
2. Step 2: Convert to fraction form
   489.50/561.50 = 561.50/x
3. Step 3: Cross multiply
   489.50x = 561.50 × 561.50
4. Step 4: Simplify right side
   489.50x = 315,282.25
5. Step 5: Solve for x
   x = 315,282.25/489.50
6. Step 6: Final answer
   x = 644.09