Finding the Fourth Proportional to 85.83, 128.73 and 28.05

Step by Step Solution

1. Step 1: Write the proportion equation
   85.83 : 128.73 = 28.05 : x
2. Step 2: Convert to fraction form
   85.83/128.73 = 28.05/x
3. Step 3: Cross multiply
   85.83x = 128.73 × 28.05
4. Step 4: Simplify right side
   85.83x = 3,610.88
5. Step 5: Solve for x
   x = 3,610.88/85.83
6. Step 6: Final answer
   x = 42.07