Finding the Third Proportional to 120.66 and 287.72

Step by Step Solution

1. Step 1: Write the proportion equation
   120.66 : 287.72 = 287.72 : x
2. Step 2: Convert to fraction form
   120.66/287.72 = 287.72/x
3. Step 3: Cross multiply
   120.66x = 287.72 × 287.72
4. Step 4: Simplify right side
   120.66x = 82,782.08
5. Step 5: Solve for x
   x = 82,782.08/120.66
6. Step 6: Final answer
   x = 686.10