Finding the Third Proportional to 213.89 and 321.47

Step by Step Solution

1. Step 1: Write the proportion equation
   213.89 : 321.47 = 321.47 : x
2. Step 2: Convert to fraction form
   213.89/321.47 = 321.47/x
3. Step 3: Cross multiply
   213.89x = 321.47 × 321.47
4. Step 4: Simplify right side
   213.89x = 103,342.16
5. Step 5: Solve for x
   x = 103,342.16/213.89
6. Step 6: Final answer
   x = 483.15