Finding the Fourth Proportional to 142.55, 196.58 and 121.89

Step by Step Solution

1. Step 1: Write the proportion equation
   142.55 : 196.58 = 121.89 : x
2. Step 2: Convert to fraction form
   142.55/196.58 = 121.89/x
3. Step 3: Cross multiply
   142.55x = 196.58 × 121.89
4. Step 4: Simplify right side
   142.55x = 23,960.53
5. Step 5: Solve for x
   x = 23,960.53/142.55
6. Step 6: Final answer
   x = 168.09