Finding the Fourth Proportional to 78.72, 108.90 and 75.72

Step by Step Solution

1. Step 1: Write the proportion equation
   78.72 : 108.90 = 75.72 : x
2. Step 2: Convert to fraction form
   78.72/108.90 = 75.72/x
3. Step 3: Cross multiply
   78.72x = 108.90 × 75.72
4. Step 4: Simplify right side
   78.72x = 8,245.91
5. Step 5: Solve for x
   x = 8,245.91/78.72
6. Step 6: Final answer
   x = 104.75