Finding the Third Proportional to 428.25 and 670.50

Step by Step Solution

1. Step 1: Write the proportion equation
   428.25 : 670.50 = 670.50 : x
2. Step 2: Convert to fraction form
   428.25/670.50 = 670.50/x
3. Step 3: Cross multiply
   428.25x = 670.50 × 670.50
4. Step 4: Simplify right side
   428.25x = 449,570.25
5. Step 5: Solve for x
   x = 449,570.25/428.25
6. Step 6: Final answer
   x = 1,049.78