Finding the Fourth Proportional to 85.53, 128.22 and 42.81

Step by Step Solution

1. Step 1: Write the proportion equation
   85.53 : 128.22 = 42.81 : x
2. Step 2: Convert to fraction form
   85.53/128.22 = 42.81/x
3. Step 3: Cross multiply
   85.53x = 128.22 × 42.81
4. Step 4: Simplify right side
   85.53x = 5,489.10
5. Step 5: Solve for x
   x = 5,489.10/85.53
6. Step 6: Final answer
   x = 64.18