Finding the Third Proportional to 689.50 and 791.50

Step by Step Solution

1. Step 1: Write the proportion equation
   689.50 : 791.50 = 791.50 : x
2. Step 2: Convert to fraction form
   689.50/791.50 = 791.50/x
3. Step 3: Cross multiply
   689.50x = 791.50 × 791.50
4. Step 4: Simplify right side
   689.50x = 626,472.25
5. Step 5: Solve for x
   x = 626,472.25/689.50
6. Step 6: Final answer
   x = 908.59