Finding the Fourth Proportional to 142.42, 196.34 and 121.91

Step by Step Solution

1. Step 1: Write the proportion equation
   142.42 : 196.34 = 121.91 : x
2. Step 2: Convert to fraction form
   142.42/196.34 = 121.91/x
3. Step 3: Cross multiply
   142.42x = 196.34 × 121.91
4. Step 4: Simplify right side
   142.42x = 23,935.81
5. Step 5: Solve for x
   x = 23,935.81/142.42
6. Step 6: Final answer
   x = 168.06