Finding the Fourth Proportional to 103.12, 142.42 and 86.58

Step by Step Solution

1. Step 1: Write the proportion equation
   103.12 : 142.42 = 86.58 : x
2. Step 2: Convert to fraction form
   103.12/142.42 = 86.58/x
3. Step 3: Cross multiply
   103.12x = 142.42 × 86.58
4. Step 4: Simplify right side
   103.12x = 12,330.72
5. Step 5: Solve for x
   x = 12,330.72/103.12
6. Step 6: Final answer
   x = 119.58