Finding the Fourth Proportional to 72.48, 108.72 and 64.80

Step by Step Solution

1. Step 1: Write the proportion equation
   72.48 : 108.72 = 64.80 : x
2. Step 2: Convert to fraction form
   72.48/108.72 = 64.80/x
3. Step 3: Cross multiply
   72.48x = 108.72 × 64.80
4. Step 4: Simplify right side
   72.48x = 7,045.06
5. Step 5: Solve for x
   x = 7,045.06/72.48
6. Step 6: Final answer
   x = 97.20