Finding the Fourth Proportional to 105.19, 145.33 and 89.10

Step by Step Solution

1. Step 1: Write the proportion equation
   105.19 : 145.33 = 89.10 : x
2. Step 2: Convert to fraction form
   105.19/145.33 = 89.10/x
3. Step 3: Cross multiply
   105.19x = 145.33 × 89.10
4. Step 4: Simplify right side
   105.19x = 12,948.90
5. Step 5: Solve for x
   x = 12,948.90/105.19
6. Step 6: Final answer
   x = 123.10