Finding the Fourth Proportional to 111.17, 166.05 and 100.31

Step by Step Solution

1. Step 1: Write the proportion equation
   111.17 : 166.05 = 100.31 : x
2. Step 2: Convert to fraction form
   111.17/166.05 = 100.31/x
3. Step 3: Cross multiply
   111.17x = 166.05 × 100.31
4. Step 4: Simplify right side
   111.17x = 16,655.97
5. Step 5: Solve for x
   x = 16,655.97/111.17
6. Step 6: Final answer
   x = 149.83