Finding the Fourth Proportional to 111.72, 154.28 and 100.08

Step by Step Solution

1. Step 1: Write the proportion equation
   111.72 : 154.28 = 100.08 : x
2. Step 2: Convert to fraction form
   111.72/154.28 = 100.08/x
3. Step 3: Cross multiply
   111.72x = 154.28 × 100.08
4. Step 4: Simplify right side
   111.72x = 15,440.34
5. Step 5: Solve for x
   x = 15,440.34/111.72
6. Step 6: Final answer
   x = 138.21