Finding the Fourth Proportional to 111.05, 153.35 and 81.71

Step by Step Solution

1. Step 1: Write the proportion equation
   111.05 : 153.35 = 81.71 : x
2. Step 2: Convert to fraction form
   111.05/153.35 = 81.71/x
3. Step 3: Cross multiply
   111.05x = 153.35 × 81.71
4. Step 4: Simplify right side
   111.05x = 12,529.82
5. Step 5: Solve for x
   x = 12,529.82/111.05
6. Step 6: Final answer
   x = 112.83