Finding the Fourth Proportional to 85.58, 128.37 and 42.28

Step by Step Solution

1. Step 1: Write the proportion equation
   85.58 : 128.37 = 42.28 : x
2. Step 2: Convert to fraction form
   85.58/128.37 = 42.28/x
3. Step 3: Cross multiply
   85.58x = 128.37 × 42.28
4. Step 4: Simplify right side
   85.58x = 5,427.48
5. Step 5: Solve for x
   x = 5,427.48/85.58
6. Step 6: Final answer
   x = 63.42