Finding the Third Proportional to 691.31 and 1,040.91

Step by Step Solution

1. Step 1: Write the proportion equation
   691.31 : 1,040.91 = 1,040.91 : x
2. Step 2: Convert to fraction form
   691.31/1,040.91 = 1,040.91/x
3. Step 3: Cross multiply
   691.31x = 1,040.91 × 1,040.91
4. Step 4: Simplify right side
   691.31x = 1,083,485.82
5. Step 5: Solve for x
   x = 1,083,485.82/691.31
6. Step 6: Final answer
   x = 1,567.29