Finding the Fourth Proportional to 142.17, 196.18 and 86.91

Step by Step Solution

1. Step 1: Write the proportion equation
   142.17 : 196.18 = 86.91 : x
2. Step 2: Convert to fraction form
   142.17/196.18 = 86.91/x
3. Step 3: Cross multiply
   142.17x = 196.18 × 86.91
4. Step 4: Simplify right side
   142.17x = 17,050.00
5. Step 5: Solve for x
   x = 17,050.00/142.17
6. Step 6: Final answer
   x = 119.93