Finding the Fourth Proportional to 72.91, 109.16 and 72.57

Step by Step Solution

1. Step 1: Write the proportion equation
   72.91 : 109.16 = 72.57 : x
2. Step 2: Convert to fraction form
   72.91/109.16 = 72.57/x
3. Step 3: Cross multiply
   72.91x = 109.16 × 72.57
4. Step 4: Simplify right side
   72.91x = 7,921.74
5. Step 5: Solve for x
   x = 7,921.74/72.91
6. Step 6: Final answer
   x = 108.65