Finding the Fourth Proportional to 111.51, 153.89 and 72.18

Step by Step Solution

1. Step 1: Write the proportion equation
   111.51 : 153.89 = 72.18 : x
2. Step 2: Convert to fraction form
   111.51/153.89 = 72.18/x
3. Step 3: Cross multiply
   111.51x = 153.89 × 72.18
4. Step 4: Simplify right side
   111.51x = 11,107.42
5. Step 5: Solve for x
   x = 11,107.42/111.51
6. Step 6: Final answer
   x = 99.61