Finding the Fourth Proportional to 85.46, 128.22 and 42.17

Step by Step Solution

1. Step 1: Write the proportion equation
   85.46 : 128.22 = 42.17 : x
2. Step 2: Convert to fraction form
   85.46/128.22 = 42.17/x
3. Step 3: Cross multiply
   85.46x = 128.22 × 42.17
4. Step 4: Simplify right side
   85.46x = 5,406.95
5. Step 5: Solve for x
   x = 5,406.95/85.46
6. Step 6: Final answer
   x = 63.27