Finding the Fourth Proportional to 111.97, 154.56 and 87.31

Step by Step Solution

1. Step 1: Write the proportion equation
   111.97 : 154.56 = 87.31 : x
2. Step 2: Convert to fraction form
   111.97/154.56 = 87.31/x
3. Step 3: Cross multiply
   111.97x = 154.56 × 87.31
4. Step 4: Simplify right side
   111.97x = 13,494.63
5. Step 5: Solve for x
   x = 13,494.63/111.97
6. Step 6: Final answer
   x = 120.52