Finding the Fourth Proportional to 85.72, 128.82 and 82.48

Step by Step Solution

1. Step 1: Write the proportion equation
   85.72 : 128.82 = 82.48 : x
2. Step 2: Convert to fraction form
   85.72/128.82 = 82.48/x
3. Step 3: Cross multiply
   85.72x = 128.82 × 82.48
4. Step 4: Simplify right side
   85.72x = 10,625.07
5. Step 5: Solve for x
   x = 10,625.07/85.72
6. Step 6: Final answer
   x = 123.95