Finding the Fourth Proportional to 85.50, 128.25 and 79.83

Step by Step Solution

1. Step 1: Write the proportion equation
   85.50 : 128.25 = 79.83 : x
2. Step 2: Convert to fraction form
   85.50/128.25 = 79.83/x
3. Step 3: Cross multiply
   85.50x = 128.25 × 79.83
4. Step 4: Simplify right side
   85.50x = 10,238.20
5. Step 5: Solve for x
   x = 10,238.20/85.50
6. Step 6: Final answer
   x = 119.75