Finding the Fourth Proportional to 85.55, 128.42 and 56.58

Step by Step Solution

1. Step 1: Write the proportion equation
   85.55 : 128.42 = 56.58 : x
2. Step 2: Convert to fraction form
   85.55/128.42 = 56.58/x
3. Step 3: Cross multiply
   85.55x = 128.42 × 56.58
4. Step 4: Simplify right side
   85.55x = 7,265.72
5. Step 5: Solve for x
   x = 7,265.72/85.55
6. Step 6: Final answer
   x = 84.93