Finding the Fourth Proportional to 111.50, 153.76 and 72.15

Step by Step Solution

1. Step 1: Write the proportion equation
   111.50 : 153.76 = 72.15 : x
2. Step 2: Convert to fraction form
   111.50/153.76 = 72.15/x
3. Step 3: Cross multiply
   111.50x = 153.76 × 72.15
4. Step 4: Simplify right side
   111.50x = 11,093.42
5. Step 5: Solve for x
   x = 11,093.42/111.50
6. Step 6: Final answer
   x = 99.50