Finding the Third Proportional to 644.63 and 978.38

Step by Step Solution

1. Step 1: Write the proportion equation
   644.63 : 978.38 = 978.38 : x
2. Step 2: Convert to fraction form
   644.63/978.38 = 978.38/x
3. Step 3: Cross multiply
   644.63x = 978.38 × 978.38
4. Step 4: Simplify right side
   644.63x = 957,217.64
5. Step 5: Solve for x
   x = 957,217.64/644.63
6. Step 6: Final answer
   x = 1,484.92