Finding the Fourth Proportional to 72.48, 108.78 and 54.50

Step by Step Solution

1. Step 1: Write the proportion equation
   72.48 : 108.78 = 54.50 : x
2. Step 2: Convert to fraction form
   72.48/108.78 = 54.50/x
3. Step 3: Cross multiply
   72.48x = 108.78 × 54.50
4. Step 4: Simplify right side
   72.48x = 5,927.97
5. Step 5: Solve for x
   x = 5,927.97/72.48
6. Step 6: Final answer
   x = 81.79