Finding the Third Proportional to 688.50 and 1,507.31

Step by Step Solution

1. Step 1: Write the proportion equation
   688.50 : 1,507.31 = 1,507.31 : x
2. Step 2: Convert to fraction form
   688.50/1,507.31 = 1,507.31/x
3. Step 3: Cross multiply
   688.50x = 1,507.31 × 1,507.31
4. Step 4: Simplify right side
   688.50x = 2,271,990.97
5. Step 5: Solve for x
   x = 2,271,990.97/688.50
6. Step 6: Final answer
   x = 3,299.91