Finding the Fourth Proportional to 85.32, 128.01 and 42.57

Step by Step Solution

1. Step 1: Write the proportion equation
   85.32 : 128.01 = 42.57 : x
2. Step 2: Convert to fraction form
   85.32/128.01 = 42.57/x
3. Step 3: Cross multiply
   85.32x = 128.01 × 42.57
4. Step 4: Simplify right side
   85.32x = 5,449.39
5. Step 5: Solve for x
   x = 5,449.39/85.32
6. Step 6: Final answer
   x = 63.87