Finding the Third Proportional to 120.50 and 258.50

Step by Step Solution

1. Step 1: Write the proportion equation
   120.50 : 258.50 = 258.50 : x
2. Step 2: Convert to fraction form
   120.50/258.50 = 258.50/x
3. Step 3: Cross multiply
   120.50x = 258.50 × 258.50
4. Step 4: Simplify right side
   120.50x = 66,822.25
5. Step 5: Solve for x
   x = 66,822.25/120.50
6. Step 6: Final answer
   x = 554.54