Finding the Fourth Proportional to 89.86, 123.69 and 81.09

Step by Step Solution

1. Step 1: Write the proportion equation
   89.86 : 123.69 = 81.09 : x
2. Step 2: Convert to fraction form
   89.86/123.69 = 81.09/x
3. Step 3: Cross multiply
   89.86x = 123.69 × 81.09
4. Step 4: Simplify right side
   89.86x = 10,030.02
5. Step 5: Solve for x
   x = 10,030.02/89.86
6. Step 6: Final answer
   x = 111.62