Finding the Third Proportional to 644.50 and 761.50

Step by Step Solution

1. Step 1: Write the proportion equation
   644.50 : 761.50 = 761.50 : x
2. Step 2: Convert to fraction form
   644.50/761.50 = 761.50/x
3. Step 3: Cross multiply
   644.50x = 761.50 × 761.50
4. Step 4: Simplify right side
   644.50x = 579,882.25
5. Step 5: Solve for x
   x = 579,882.25/644.50
6. Step 6: Final answer
   x = 899.74