Finding the Fourth Proportional to 108.72, 162.91 and 78.23

Step by Step Solution

1. Step 1: Write the proportion equation
   108.72 : 162.91 = 78.23 : x
2. Step 2: Convert to fraction form
   108.72/162.91 = 78.23/x
3. Step 3: Cross multiply
   108.72x = 162.91 × 78.23
4. Step 4: Simplify right side
   108.72x = 12,744.95
5. Step 5: Solve for x
   x = 12,744.95/108.72
6. Step 6: Final answer
   x = 117.23