Finding the Fourth Proportional to 111.55, 153.87 and 72.17

Step by Step Solution

1. Step 1: Write the proportion equation
   111.55 : 153.87 = 72.17 : x
2. Step 2: Convert to fraction form
   111.55/153.87 = 72.17/x
3. Step 3: Cross multiply
   111.55x = 153.87 × 72.17
4. Step 4: Simplify right side
   111.55x = 11,104.80
5. Step 5: Solve for x
   x = 11,104.80/111.55
6. Step 6: Final answer
   x = 99.55