Finding the Fourth Proportional to 86.12, 129.22 and 42.81

Step by Step Solution

1. Step 1: Write the proportion equation
   86.12 : 129.22 = 42.81 : x
2. Step 2: Convert to fraction form
   86.12/129.22 = 42.81/x
3. Step 3: Cross multiply
   86.12x = 129.22 × 42.81
4. Step 4: Simplify right side
   86.12x = 5,531.89
5. Step 5: Solve for x
   x = 5,531.89/86.12
6. Step 6: Final answer
   x = 64.24