Finding the Third Proportional to 691.50 and 775.50

Step by Step Solution

1. Step 1: Write the proportion equation
   691.50 : 775.50 = 775.50 : x
2. Step 2: Convert to fraction form
   691.50/775.50 = 775.50/x
3. Step 3: Cross multiply
   691.50x = 775.50 × 775.50
4. Step 4: Simplify right side
   691.50x = 601,400.25
5. Step 5: Solve for x
   x = 601,400.25/691.50
6. Step 6: Final answer
   x = 869.70