Finding the Fourth Proportional to 85.71, 128.59 and 42.38

Step by Step Solution

1. Step 1: Write the proportion equation
   85.71 : 128.59 = 42.38 : x
2. Step 2: Convert to fraction form
   85.71/128.59 = 42.38/x
3. Step 3: Cross multiply
   85.71x = 128.59 × 42.38
4. Step 4: Simplify right side
   85.71x = 5,448.90
5. Step 5: Solve for x
   x = 5,448.90/85.71
6. Step 6: Final answer
   x = 63.57