Finding the Fourth Proportional to 111.09, 165.47 and 105.31

Step by Step Solution

1. Step 1: Write the proportion equation
   111.09 : 165.47 = 105.31 : x
2. Step 2: Convert to fraction form
   111.09/165.47 = 105.31/x
3. Step 3: Cross multiply
   111.09x = 165.47 × 105.31
4. Step 4: Simplify right side
   111.09x = 17,425.65
5. Step 5: Solve for x
   x = 17,425.65/111.09
6. Step 6: Final answer
   x = 156.86