Finding the Fourth Proportional to 72.50, 108.79 and 54.50

Step by Step Solution

1. Step 1: Write the proportion equation
   72.50 : 108.79 = 54.50 : x
2. Step 2: Convert to fraction form
   72.50/108.79 = 54.50/x
3. Step 3: Cross multiply
   72.50x = 108.79 × 54.50
4. Step 4: Simplify right side
   72.50x = 5,928.37
5. Step 5: Solve for x
   x = 5,928.37/72.50
6. Step 6: Final answer
   x = 81.78