Finding the Fourth Proportional to 111.05, 153.16 and 71.72

Step by Step Solution

1. Step 1: Write the proportion equation
   111.05 : 153.16 = 71.72 : x
2. Step 2: Convert to fraction form
   111.05/153.16 = 71.72/x
3. Step 3: Cross multiply
   111.05x = 153.16 × 71.72
4. Step 4: Simplify right side
   111.05x = 10,983.87
5. Step 5: Solve for x
   x = 10,983.87/111.05
6. Step 6: Final answer
   x = 98.91