Finding the Fourth Proportional to 85.60, 128.32 and 42.28

Step by Step Solution

1. Step 1: Write the proportion equation
   85.60 : 128.32 = 42.28 : x
2. Step 2: Convert to fraction form
   85.60/128.32 = 42.28/x
3. Step 3: Cross multiply
   85.60x = 128.32 × 42.28
4. Step 4: Simplify right side
   85.60x = 5,425.37
5. Step 5: Solve for x
   x = 5,425.37/85.60
6. Step 6: Final answer
   x = 63.38