Finding the Third Proportional to 142.31 and 215.72

Step by Step Solution

1. Step 1: Write the proportion equation
   142.31 : 215.72 = 215.72 : x
2. Step 2: Convert to fraction form
   142.31/215.72 = 215.72/x
3. Step 3: Cross multiply
   142.31x = 215.72 × 215.72
4. Step 4: Simplify right side
   142.31x = 46,534.58
5. Step 5: Solve for x
   x = 46,534.58/142.31
6. Step 6: Final answer
   x = 326.99