Finding the Fourth Proportional to 85.98, 128.89 and 55.47

Step by Step Solution

1. Step 1: Write the proportion equation
   85.98 : 128.89 = 55.47 : x
2. Step 2: Convert to fraction form
   85.98/128.89 = 55.47/x
3. Step 3: Cross multiply
   85.98x = 128.89 × 55.47
4. Step 4: Simplify right side
   85.98x = 7,149.53
5. Step 5: Solve for x
   x = 7,149.53/85.98
6. Step 6: Final answer
   x = 83.15