Finding the Fourth Proportional to 105.54, 145.42 and 89.20

Step by Step Solution

1. Step 1: Write the proportion equation
   105.54 : 145.42 = 89.20 : x
2. Step 2: Convert to fraction form
   105.54/145.42 = 89.20/x
3. Step 3: Cross multiply
   105.54x = 145.42 × 89.20
4. Step 4: Simplify right side
   105.54x = 12,971.46
5. Step 5: Solve for x
   x = 12,971.46/105.54
6. Step 6: Final answer
   x = 122.91