Finding the Fourth Proportional to 108.72, 162.93 and 78.15

Step by Step Solution

1. Step 1: Write the proportion equation
   108.72 : 162.93 = 78.15 : x
2. Step 2: Convert to fraction form
   108.72/162.93 = 78.15/x
3. Step 3: Cross multiply
   108.72x = 162.93 × 78.15
4. Step 4: Simplify right side
   108.72x = 12,732.98
5. Step 5: Solve for x
   x = 12,732.98/108.72
6. Step 6: Final answer
   x = 117.12