Finding the Fourth Proportional to 111.51, 153.81 and 72.15

Step by Step Solution

1. Step 1: Write the proportion equation
   111.51 : 153.81 = 72.15 : x
2. Step 2: Convert to fraction form
   111.51/153.81 = 72.15/x
3. Step 3: Cross multiply
   111.51x = 153.81 × 72.15
4. Step 4: Simplify right side
   111.51x = 11,096.83
5. Step 5: Solve for x
   x = 11,096.83/111.51
6. Step 6: Final answer
   x = 99.52