Finding the Fourth Proportional to 108.86, 163.42 and 78.34

Step by Step Solution

1. Step 1: Write the proportion equation
   108.86 : 163.42 = 78.34 : x
2. Step 2: Convert to fraction form
   108.86/163.42 = 78.34/x
3. Step 3: Cross multiply
   108.86x = 163.42 × 78.34
4. Step 4: Simplify right side
   108.86x = 12,801.72
5. Step 5: Solve for x
   x = 12,801.72/108.86
6. Step 6: Final answer
   x = 117.60