Finding the Fourth Proportional to 115.58, 159.55 and 78.72

Step by Step Solution

1. Step 1: Write the proportion equation
   115.58 : 159.55 = 78.72 : x
2. Step 2: Convert to fraction form
   115.58/159.55 = 78.72/x
3. Step 3: Cross multiply
   115.58x = 159.55 × 78.72
4. Step 4: Simplify right side
   115.58x = 12,559.78
5. Step 5: Solve for x
   x = 12,559.78/115.58
6. Step 6: Final answer
   x = 108.67