Finding the Fourth Proportional to 85.41, 128.18 and 42.10

Step by Step Solution

1. Step 1: Write the proportion equation
   85.41 : 128.18 = 42.10 : x
2. Step 2: Convert to fraction form
   85.41/128.18 = 42.10/x
3. Step 3: Cross multiply
   85.41x = 128.18 × 42.10
4. Step 4: Simplify right side
   85.41x = 5,396.38
5. Step 5: Solve for x
   x = 5,396.38/85.41
6. Step 6: Final answer
   x = 63.18