Finding the Third Proportional to 685.86 and 1,618.42

Step by Step Solution

1. Step 1: Write the proportion equation
   685.86 : 1,618.42 = 1,618.42 : x
2. Step 2: Convert to fraction form
   685.86/1,618.42 = 1,618.42/x
3. Step 3: Cross multiply
   685.86x = 1,618.42 × 1,618.42
4. Step 4: Simplify right side
   685.86x = 2,619,276.72
5. Step 5: Solve for x
   x = 2,619,276.72/685.86
6. Step 6: Final answer
   x = 3,818.95