Finding the Fourth Proportional to 111.41, 153.86 and 86.61

Step by Step Solution

1. Step 1: Write the proportion equation
   111.41 : 153.86 = 86.61 : x
2. Step 2: Convert to fraction form
   111.41/153.86 = 86.61/x
3. Step 3: Cross multiply
   111.41x = 153.86 × 86.61
4. Step 4: Simplify right side
   111.41x = 13,326.03
5. Step 5: Solve for x
   x = 13,326.03/111.41
6. Step 6: Final answer
   x = 119.61