Finding the Fourth Proportional to 111.20, 153.25 and 90.55

Step by Step Solution

1. Step 1: Write the proportion equation
   111.20 : 153.25 = 90.55 : x
2. Step 2: Convert to fraction form
   111.20/153.25 = 90.55/x
3. Step 3: Cross multiply
   111.20x = 153.25 × 90.55
4. Step 4: Simplify right side
   111.20x = 13,876.79
5. Step 5: Solve for x
   x = 13,876.79/111.20
6. Step 6: Final answer
   x = 124.79