Finding the Third Proportional to 213.57 and 319.89

Step by Step Solution

1. Step 1: Write the proportion equation
   213.57 : 319.89 = 319.89 : x
2. Step 2: Convert to fraction form
   213.57/319.89 = 319.89/x
3. Step 3: Cross multiply
   213.57x = 319.89 × 319.89
4. Step 4: Simplify right side
   213.57x = 102,327.51
5. Step 5: Solve for x
   x = 102,327.51/213.57
6. Step 6: Final answer
   x = 479.12