Finding the Fourth Proportional to 142.57, 213.72 and 81.62

Step by Step Solution

1. Step 1: Write the proportion equation
   142.57 : 213.72 = 81.62 : x
2. Step 2: Convert to fraction form
   142.57/213.72 = 81.62/x
3. Step 3: Cross multiply
   142.57x = 213.72 × 81.62
4. Step 4: Simplify right side
   142.57x = 17,443.83
5. Step 5: Solve for x
   x = 17,443.83/142.57
6. Step 6: Final answer
   x = 122.35