Finding the Fourth Proportional to 78.72, 108.72 and 56.88

Step by Step Solution

1. Step 1: Write the proportion equation
   78.72 : 108.72 = 56.88 : x
2. Step 2: Convert to fraction form
   78.72/108.72 = 56.88/x
3. Step 3: Cross multiply
   78.72x = 108.72 × 56.88
4. Step 4: Simplify right side
   78.72x = 6,183.99
5. Step 5: Solve for x
   x = 6,183.99/78.72
6. Step 6: Final answer
   x = 78.56