Finding the Third Proportional to 691.50 and 1,066.31

Step by Step Solution

1. Step 1: Write the proportion equation
   691.50 : 1,066.31 = 1,066.31 : x
2. Step 2: Convert to fraction form
   691.50/1,066.31 = 1,066.31/x
3. Step 3: Cross multiply
   691.50x = 1,066.31 × 1,066.31
4. Step 4: Simplify right side
   691.50x = 1,137,022.35
5. Step 5: Solve for x
   x = 1,137,022.35/691.50
6. Step 6: Final answer
   x = 1,644.28