Finding the Third Proportional to 643.50 and 1,308

Step by Step Solution

1. Step 1: Write the proportion equation
   643.50 : 1,308 = 1,308 : x
2. Step 2: Convert to fraction form
   643.50/1,308 = 1,308/x
3. Step 3: Cross multiply
   643.50x = 1,308 × 1,308
4. Step 4: Simplify right side
   643.50x = 1,710,864
5. Step 5: Solve for x
   x = 1,710,864/643.50
6. Step 6: Final answer
   x = 2,658.69