Finding the Fourth Proportional to 85.79, 128.69 and 28.01

Step by Step Solution

1. Step 1: Write the proportion equation
   85.79 : 128.69 = 28.01 : x
2. Step 2: Convert to fraction form
   85.79/128.69 = 28.01/x
3. Step 3: Cross multiply
   85.79x = 128.69 × 28.01
4. Step 4: Simplify right side
   85.79x = 3,603.82
5. Step 5: Solve for x
   x = 3,603.82/85.79
6. Step 6: Final answer
   x = 42.01