Finding the Third Proportional to 218.60 and 385.83

Step by Step Solution

1. Step 1: Write the proportion equation
   218.60 : 385.83 = 385.83 : x
2. Step 2: Convert to fraction form
   218.60/385.83 = 385.83/x
3. Step 3: Cross multiply
   218.60x = 385.83 × 385.83
4. Step 4: Simplify right side
   218.60x = 148,863.34
5. Step 5: Solve for x
   x = 148,863.34/218.60
6. Step 6: Final answer
   x = 680.98