Finding the Fourth Proportional to 85.49, 128.19 and 42.16

Step by Step Solution

1. Step 1: Write the proportion equation
   85.49 : 128.19 = 42.16 : x
2. Step 2: Convert to fraction form
   85.49/128.19 = 42.16/x
3. Step 3: Cross multiply
   85.49x = 128.19 × 42.16
4. Step 4: Simplify right side
   85.49x = 5,404.49
5. Step 5: Solve for x
   x = 5,404.49/85.49
6. Step 6: Final answer
   x = 63.22