Finding the Third Proportional to 428 and 488.50

Step by Step Solution

1. Step 1: Write the proportion equation
   428 : 488.50 = 488.50 : x
2. Step 2: Convert to fraction form
   428/488.50 = 488.50/x
3. Step 3: Cross multiply
   428x = 488.50 × 488.50
4. Step 4: Simplify right side
   428x = 238,632.25
5. Step 5: Solve for x
   x = 238,632.25/428
6. Step 6: Final answer
   x = 557.55