Finding the Fourth Proportional to 111.87, 167.55 and 86.00

Step by Step Solution

1. Step 1: Write the proportion equation
   111.87 : 167.55 = 86.00 : x
2. Step 2: Convert to fraction form
   111.87/167.55 = 86.00/x
3. Step 3: Cross multiply
   111.87x = 167.55 × 86.00
4. Step 4: Simplify right side
   111.87x = 14,408.94
5. Step 5: Solve for x
   x = 14,408.94/111.87
6. Step 6: Final answer
   x = 128.81