Finding the Fourth Proportional to 85.61, 128.41 and 42.26

Step by Step Solution

1. Step 1: Write the proportion equation
   85.61 : 128.41 = 42.26 : x
2. Step 2: Convert to fraction form
   85.61/128.41 = 42.26/x
3. Step 3: Cross multiply
   85.61x = 128.41 × 42.26
4. Step 4: Simplify right side
   85.61x = 5,426.82
5. Step 5: Solve for x
   x = 5,426.82/85.61
6. Step 6: Final answer
   x = 63.39