Finding the Fourth Proportional to 111.72, 153.96 and 82.20

Step by Step Solution

1. Step 1: Write the proportion equation
   111.72 : 153.96 = 82.20 : x
2. Step 2: Convert to fraction form
   111.72/153.96 = 82.20/x
3. Step 3: Cross multiply
   111.72x = 153.96 × 82.20
4. Step 4: Simplify right side
   111.72x = 12,655.51
5. Step 5: Solve for x
   x = 12,655.51/111.72
6. Step 6: Final answer
   x = 113.28