Finding the Fourth Proportional to 111.90, 153.06 and 109.20

Step by Step Solution

1. Step 1: Write the proportion equation
   111.90 : 153.06 = 109.20 : x
2. Step 2: Convert to fraction form
   111.90/153.06 = 109.20/x
3. Step 3: Cross multiply
   111.90x = 153.06 × 109.20
4. Step 4: Simplify right side
   111.90x = 16,714.15
5. Step 5: Solve for x
   x = 16,714.15/111.90
6. Step 6: Final answer
   x = 149.37