Finding the Fourth Proportional to 111.88, 154.50 and 90.10

Step by Step Solution

1. Step 1: Write the proportion equation
   111.88 : 154.50 = 90.10 : x
2. Step 2: Convert to fraction form
   111.88/154.50 = 90.10/x
3. Step 3: Cross multiply
   111.88x = 154.50 × 90.10
4. Step 4: Simplify right side
   111.88x = 13,920.45
5. Step 5: Solve for x
   x = 13,920.45/111.88
6. Step 6: Final answer
   x = 124.42