Finding the Fourth Proportional to 85.71, 128.60 and 42.42

Step by Step Solution

1. Step 1: Write the proportion equation
   85.71 : 128.60 = 42.42 : x
2. Step 2: Convert to fraction form
   85.71/128.60 = 42.42/x
3. Step 3: Cross multiply
   85.71x = 128.60 × 42.42
4. Step 4: Simplify right side
   85.71x = 5,454.89
5. Step 5: Solve for x
   x = 5,454.89/85.71
6. Step 6: Final answer
   x = 63.65