Finding the Third Proportional to 644.25 and 978.63

Step by Step Solution

1. Step 1: Write the proportion equation
   644.25 : 978.63 = 978.63 : x
2. Step 2: Convert to fraction form
   644.25/978.63 = 978.63/x
3. Step 3: Cross multiply
   644.25x = 978.63 × 978.63
4. Step 4: Simplify right side
   644.25x = 957,706.89
5. Step 5: Solve for x
   x = 957,706.89/644.25
6. Step 6: Final answer
   x = 1,486.55