Finding the Third Proportional to 611.81 and 871.69

Step by Step Solution

1. Step 1: Write the proportion equation
   611.81 : 871.69 = 871.69 : x
2. Step 2: Convert to fraction form
   611.81/871.69 = 871.69/x
3. Step 3: Cross multiply
   611.81x = 871.69 × 871.69
4. Step 4: Simplify right side
   611.81x = 759,839.10
5. Step 5: Solve for x
   x = 759,839.10/611.81
6. Step 6: Final answer
   x = 1,241.95