Finding the Fourth Proportional to 142.56, 196.71 and 86.55

Step by Step Solution

1. Step 1: Write the proportion equation
   142.56 : 196.71 = 86.55 : x
2. Step 2: Convert to fraction form
   142.56/196.71 = 86.55/x
3. Step 3: Cross multiply
   142.56x = 196.71 × 86.55
4. Step 4: Simplify right side
   142.56x = 17,025.25
5. Step 5: Solve for x
   x = 17,025.25/142.56
6. Step 6: Final answer
   x = 119.43