Finding the Fourth Proportional to 142.88, 212.72 and 139.52

Step by Step Solution

1. Step 1: Write the proportion equation
   142.88 : 212.72 = 139.52 : x
2. Step 2: Convert to fraction form
   142.88/212.72 = 139.52/x
3. Step 3: Cross multiply
   142.88x = 212.72 × 139.52
4. Step 4: Simplify right side
   142.88x = 29,678.69
5. Step 5: Solve for x
   x = 29,678.69/142.88
6. Step 6: Final answer
   x = 207.72