Finding the Fourth Proportional to 111.01, 166.58 and 85.50

Step by Step Solution

1. Step 1: Write the proportion equation
   111.01 : 166.58 = 85.50 : x
2. Step 2: Convert to fraction form
   111.01/166.58 = 85.50/x
3. Step 3: Cross multiply
   111.01x = 166.58 × 85.50
4. Step 4: Simplify right side
   111.01x = 14,241.33
5. Step 5: Solve for x
   x = 14,241.33/111.01
6. Step 6: Final answer
   x = 128.29