Finding the Fourth Proportional to 111.08, 153.20 and 72.20

Step by Step Solution

1. Step 1: Write the proportion equation
   111.08 : 153.20 = 72.20 : x
2. Step 2: Convert to fraction form
   111.08/153.20 = 72.20/x
3. Step 3: Cross multiply
   111.08x = 153.20 × 72.20
4. Step 4: Simplify right side
   111.08x = 11,061.04
5. Step 5: Solve for x
   x = 11,061.04/111.08
6. Step 6: Final answer
   x = 99.58