Finding the Fourth Proportional to 85.89, 128.83 and 28.15

Step by Step Solution

1. Step 1: Write the proportion equation
   85.89 : 128.83 = 28.15 : x
2. Step 2: Convert to fraction form
   85.89/128.83 = 28.15/x
3. Step 3: Cross multiply
   85.89x = 128.83 × 28.15
4. Step 4: Simplify right side
   85.89x = 3,627.23
5. Step 5: Solve for x
   x = 3,627.23/85.89
6. Step 6: Final answer
   x = 42.23