Finding the Fourth Proportional to 108.78, 162.78 and 78.24

Step by Step Solution

1. Step 1: Write the proportion equation
   108.78 : 162.78 = 78.24 : x
2. Step 2: Convert to fraction form
   108.78/162.78 = 78.24/x
3. Step 3: Cross multiply
   108.78x = 162.78 × 78.24
4. Step 4: Simplify right side
   108.78x = 12,735.91
5. Step 5: Solve for x
   x = 12,735.91/108.78
6. Step 6: Final answer
   x = 117.08