Finding the Third Proportional to 663.50 and 989.38

Step by Step Solution

1. Step 1: Write the proportion equation
   663.50 : 989.38 = 989.38 : x
2. Step 2: Convert to fraction form
   663.50/989.38 = 989.38/x
3. Step 3: Cross multiply
   663.50x = 989.38 × 989.38
4. Step 4: Simplify right side
   663.50x = 978,862.89
5. Step 5: Solve for x
   x = 978,862.89/663.50
6. Step 6: Final answer
   x = 1,475.30